Guide to responsible spearfishing #2

So, you’ve sussed out a nice easy dive site that isn’t in a no-fishing zone and looks like it could hold some fish.

In my last post I covered the rules and regulations around where you can/can’t spearfish. Next up in this series is a little bit about what fish to catch. The number one take away message from this post is: If you don’t recognise it, DON’T shoot it! 

What fish can I catch?

There is NO catch and release with spearfishing. If you spear a fish, it is most likely going to die. I have seen fish swimming around with spearfishing injuries, but these fish can’t swim as well as healthy fish and are more likely to suffer mortality through predation or reduced fitness. So, if you’re going to pull that trigger, make sure that your spear is pointing at something you are going to eat and be damn sure that it’s not a protected species – heavy fines apply. If you don’t recognise it, DON’T shoot it! 

The NSW DPI website has all the details of fish you are allowed to spear and their bag and size limits. Fisheries authorities in other states and countries should have a similar resource. It has pictures. Learn these species and their bag and size limits. No short-cuts here. Spend some time on this page. If a species doesn’t appear on this list, it probably isn’t regulated, but it’s also probably not fished very often, usually because it doesn’t taste very good. There are a lot of fish to learn on this list so my advice would be to pick a species that you know is abundant in your area, memorise the bag and size limits for it and only target that one species when you go spearfishing for your first time. Pick another species to memorize on your next outing and soon you will have a long list of species that you can quote the bag and size limits off the top of your head. Again, there really is no substitute for having someone experienced show you what is ok and what is not. If you don’t recognise it, DON’T shoot it! 

There are a number of good fish identification books available and I would recommend getting very familiar with these. Below are a few of my favourites. A great online resource if you can take photos is inaturalist.org. Make a profile and post some pictures asking for advice and you will find a very helpful and knowledgeable community to help you ID that fish. It will be difficult at first to tell a lot of fish apart, but you will get better at it the more time you spend in the water. If you don’t recognise it, DON’T shoot it! 

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You will learn to identify fish a lot faster if you take an active interest in it. When you’re next out in the water and see something you don’t recognise, try to memorise as much detail (or take a photo if you have a camera) and go searching for it when you get home. You’d be surprised how often google hits the mark when you search for “fish with yellow stripes”. Markings are not the only thing to look for. Look at shapes. This will often help you to identify families of fishes. Fishes in the same family often (but not always) taste similar. Look for where the fish is found – bottom dwelling, surface swimming, mid water. Look for behaviours. For example, a fish sculling with its pectoral fins is probably a wrasse. Knowledge of all of these aspects will help you to recognise fish species from a distance and in low vis and will definitely help you to avoid a nasty fine. If you don’t recognise it, DON’T shoot it!

 

What fish can’t I catch?

There are a number of protected species and unfortunately these protections can vary from state to state. On top of this there are also Commonwealth protected species so you need to check a couple of places. For Commonwealth protected species check out this page. It’s not the easiest page to navigate, but if you find a species on here it will have a lot of information and links to pictures of it. For NSW protected species look no further than the NSW DPI page. It is worth getting to know the protected species living in your area as interfering with these species can result in massive fines. A few special mentions for southern NSW are below.

Blue groper

Blue wrasse aka blue groper are off limits to spearo’s. This is because they are a naturally inquisitive fish and will swim right up to a diver to check them out. For this reason, a lot of newbies get caught out and get excited about the great big fish right at the end of their spear. DO NOT shoot these fish. Be aware that the female blue gropers (they change sex to male when the dominant male in the area dies) are brown or yellow in colour. Learn to identify this species and do not shoot them. You can have a lot of fun when these fish are around. They will hang around and check you out. Try tapping your knife on a rock – they will often swim in very close to you to see what you’re doing. Some people like to cut up sea urchins for the gropers but I advise against this practice. These fish are very capable of feeding themselves and cutting up urchins is an unnecessary waste of life.

Blue drummer

Blue Drummer

Black Drummer

This is an interesting one and not a species that I was aware of until recently. Not usually sighted in southern NSW, but there was a recent report of one so worth knowing about. I’ve included it here because it could be easily confused with the black drummer, which you can spear and which is really good eating. They (the black drummer) are fairly long lived though so make sure there is a healthy population before taking one. Info on the blue drummer can be found here.

What fish should I catch?

 Some good sustainable species for beginners

Most nearshore species are quite abundant and good for cutting your teeth on. They are also excellent eating. Some species that I recommend are luderick, bream and tarwhine. These species may take some practice as they spook easily and can move really fast. But they are often found up in the shallows which makes them good species to target while you’re learning to increase your breath hold. Red morwong are also often targeted by beginners because they don’t move much. It’s ok to target these on your first few outings, but try to move on to other species as soon as you can as morwongs are relatively long lived species. I include them here because fishing pressure is generally low and they are fairly abundant on most reefs.

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Some more challenging species

Once you gain some confidence, it’s a good idea to try for some of the faster, more challenging species. The good news is that these species taste great and the challenge makes them really exciting to catch. Most of these species are fast growing and highly fecund (good breeders) so are more sustainable than the slower growing fish.

Australian Salmon

Australian Salmon gather in large schools and will sometimes cruise past. They are more common in the winter months in NSW. The challenging part to catching one of these fish is that they are quick and the schooling behaviour makes it difficult to target a single individual. Good aim is a must on these fish as the flesh is very soft and a body shot often results in the fish tearing off your spear and slow a agonizing death. Head-shots are best for most species, but Salmon especially. Bigger is NOT better with salmon. The big ones are quite dry so aim for fish around the 30 – 50 cm mark.

Bonito

Bonito also gather in schools but are sometimes seen as solitary individuals. Bonito is one of my favourites. Dive bombing works well, but you have to be able to keep pace until the bonito turns to be able to take a shot. A good breath-hold is needed to chase one down.

Trevally

Trevally are also great eating. While not as fast as the salmon and bonito they do spook easily and their schooling behaviour can make an individual difficult to target. Stealth is required to catch these fish.

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Invertebrates

You can catch lobsters with your hands but you must not use your speargun or any other tool to obtain them. Abalone, scallops, urchins and other shellfish are also fine to take by hand (you’ll probably want a knife for abalone) but you must still abide by the bag limits. Do not dispose of abalone guts in the water. This is to reduce the transmission of a disease that severely impacted the abalone fishery a few years ago. Process them at home and bin the guts. See the applicable closure notices here for the rules on abalone.

Tasty, but think twice

Flathead

Flatties are good eating but just be aware that all of the large ones are female so bigger is NOT always better. Also, don’t shoot directly down at them. You will bend your spear in the sand. There are techniques for damping the rubbers on your gun which you should learn.

Kingfish

Kingies are a real challenge and very tasty. They do get big and they are strong so be prepared for a fight. I have bent spears whilst landing Kingfish. I don’t target Kingfish very often any more. They do grow and breed quite quickly, but they also face very high fishing pressure from recreational and commercial fisheries.

Black Drummer

Black Drummer are fairly abundant on many reefs, but they are slow growers. I catch them every now and again, but I always make sure there are plenty around before deciding to target one. Also, make sure you can tell the difference between black and silver drummer. Silver drummer are yuk (in my opinion). They get massive and swim around in large schools. You will be tempted to take a shot on one, but I wouldn’t advise it. Black drummer can change their colour and can appear silver, especially when stressed. They don’t tend to get as big as the silvers, and usually hide among the boulders. Juveniles will school like silver drummer.

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Next Issue

Hopefully this post has given you an idea of where you can find information on fish species and some things to think about in terms of sustainability. Obviously there are dozens more species than those I have listed here. The species above are common on near-shore reefs in southern NSW. I would love to hear from you about what you target. The take home message is to do your research into the species in your local area before you hit the water and of course, if you don’t recognise it, DON’T shoot it!

Next up, I will take a look at the equipment you need to get out into the water.

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Guide to responsible spearfishing #1

Spearfishing is a great way to connect with the ocean and to get some omega 3 into your diet. It is a sustainable method of fishing when done responsibly as you only take what you need and you can target the more sustainable species and sizes. Contrary to popular opinion, the average spearo doesn’t go out indiscriminately killing everything that moves. In fact I often come home with nothing. For me the pleasure comes from being in the ocean and learning about fishy behaviour. If I happen to catch a feed that’s great! but I’m just as happy to have been underwater, watching the aquatic world pass by. Last weekend I was lucky enough to swim with a pod of dolphins for a few minutes. The video below is worth a look and talks a bit about these motivations.

My impetus for writing this article comes from discussions I’ve been involved in recently regarding how difficult it is to find information on spearfishing rules and regulations. Additionally, the Christmas period is fast approaching which often brings on a spate of green spearo’s who’ve been given some brand new gear as a gift and are perhaps a little over-excited to go and catch a feed. While this excitement is understandable, I would like to see everyone enjoying this activity responsibly for many years to come.

I’ve been involved in spearfishing for many years now and I still find it difficult to find good information so I hope that this series of articles will help to bring the information together that you’ll need to get into this sport safely and responsibly. At the very least it should give you an idea of the authorities involved in regulating spearfishing activity. A lot of this will be aimed at people just starting out in spearfishing, but I hope that some of the resources will help experienced spearo’s to figure out where they can fish as well.

Before I get into it, I want to apologise for the bias toward NSW regulation in this article, but that is where I fish so it’s what I’m familiar with. Similar resources should be available from the equivalent Fisheries/land management authorities in your region.

Starting out

Spearfishing in Tonga. I’m using a homemade slingshot and the spear is the shaft from the hinge on an old chest freezer. The Tongans are a resourceful bunch!

There really is no substitute for tagging along with an experienced person. Someone who can guide you in safety and in what you can/can’t shoot. However, I realise that it’s not always possible to find someone willing to take you along. I suggest checking out some spearfishing forums and asking if anyone in your local area is happy for you to go along with them. My experience with these forums is that most people are supportive of helping out a newbie and are pretty happy to show you the ropes. But before you even get to this stage, you should do some reading – I hope the following article will provide a lot of necessary information for you. A little bit of prior knowledge will go along way toward showing an experienced buddy that you are serious about getting into this activity and that you care about the reputation of your fellow spearo’s.

Forums:
Adreno
Extreme spearfishing – Currently unavailable, but check out their facebook page

Before you get in the water

Get to know the rules for your local area. 10 minutes on google could save you a massive fine for being an idiot and spearing a protected species in a no-fishing zone. In NSW you must obtain a fishing licence. These are very easy to acquire, available at most fishing tackle shops or online here. Spearfishing is NOT allowed on scuba in NSW.

Where can I spearfish?

You’ll want to start out somewhere nice and protected. Have a look on google earth for places close to you. Identify somewhere that looks like it has good access for the time being. You’ll learn to identify good fishing areas as you progress, but for now, just find somewhere you can get in and out without too much difficulty. Headlands may offer some protection from wind and wave action depending on the direction of the wind and swell. Beaches are easy to enter and exit from, but you are only permitted to carry a spear within 20 m of the end of the beach.

An example of an easy site. Close to parking, beach entry/exit and plenty of rocky reef close by. Assuming north is toward the top of the pic, this site would get good protection from westerly winds.

In NSW, spearfishing is subject to all of the rules applying to saltwater fishers. The fisheries rules are in place in order to sustainably manage this shared resource. They may not be perfect, but take it from me, our fisheries in Australia are much healthier than regions where fisheries are unregulated. Visit the NSW DPI recreational fishing page for these rules and closures. There is NO spearfishing in freshwater in NSW. Ocean beaches (except 20 m from either end) are also off limits. A great resource for checking whether an area is closed to spearfishing is the NSW DPI Primefact available here. In addition to these closures there is a network of marine protected areas (MPAs) along the coast of NSW. MPAs consist of marine parks, aquatic reserves and special aggregation areas.

Marine parks

There are six marine parks in NSW. They have several types of zone. Usually you can fish in a general purpose (yellow) zone, but check the zoning map to make sure. There is NO fishing in red zones. Information and zoning maps are available here. There is signage at most access points to beaches within marine parks showing the zoning of the area.

Aquatic reserves

Aquatic reserves are a tricky bunch as each one differs in what you can/can’t do. Thankfully, the NSW DPI has consolidated all of this info for you and you can find out whether speafishing is allowed or not on this website.

Grey nurse shark aggregation sites

Photo Credit: Kylie Brown

Grey nurse sharks were hunted to near extinction in the 1960’s. It’s a black mark in spearfishing history, but thankfully the species is showing signs of recovery. There are several recognised grey nurse shark aggregation sites and like aquatic reserves, they vary in what you can and can’t do so make sure you check whether you can spearfish or not on this website.

A lot of scuba divers will talk about how harmless these sharks are and that’s pretty true. However be aware that these are large wild animals and you should treat them with respect. I know of at least one case of a spearo being bitten by a grey nurse shark, so just be aware. By all means, take a look if you see one – they are majestic animals, but be aware of their behaviour and take into consideration whether you are trailing dead fish on your float. Learn to recognise a pissed off shark (fast, erratic movements; pectoral fins pointed down; head arched back). They will let you know if they don’t want you around. Always give them an exit.

National parks

NSW national parks generally only manage activities on the land but there are some rules that may apply to you as a spearo accessing the water through a national park. National parks are tricky to find info about spearfishing. From what I can gather each park has its own plan of management and if that plan makes reference to spearfishing or spearguns you must comply with that. If the plan of management makes no reference to spearfishing or spearguns, then I think the regulation below applies. Plans of management are available here. The NSW National Parks and Wildlife Regulation 2009 contains the following:

National Parks and Wildlife Regulation 2009
Part 2 Division 3 Clause 20
20   Weapons
(1)  A person must not in a park:
(b)  carry or discharge or have in the person’s possession any airgun, speargun or other lethal weapon
(6)  A person does not commit an offence under subclause (1) (b) if the person carries or possesses an unloaded speargun in a park, unless a plan of management for a park or a notice erected in the park or given to the person prohibits the carrying or possession of a speargun (whether loaded or unloaded) in a park or any part of the park.
(8)  In this clause, unloaded speargun means:
(a)  an assembled rubber powered speargun that does not have the shaft engaged in the trigger mechanism and the rubbers stretched and engaged in the shaft, or
(b)  in the case of a pneumatic, spring or gas powered speargun—one that does not have the spear shaft located within the barrel of the speargun, or
   (c)  a disassembled speargun.

If you are going to be carrying your speargun through a national park, I would recommend calling the appropriate office and talking to the park manager. You shouldn’t have your gun loaded on land anyway, but ensure that it is unloaded at all times in the national park and disengage the spear shaft from the trigger mechanism. i.e. carry the spear shaft separately from the gun body.

Commonwealth National Parks

There are six Commonwealth National Parks in Australia. Kakadu NP is bordered by the sea to the north, though admittedly, I know absolutely nothing about spearfishing in the Northern Territory and I couldn’t find any reference to spearfishing on the Kakadu NP website. My advice would be to call the ranger station and ask about it if you plan on braving the crocs up there! Booderee National Park encompasses waters of Jervis Bay. Spearfishing is prohibited and spears or spear guns are not allowed in this parkNorfolk Island and Christmas Island National Parks also have oceanic boundaries and again, I could not find any reference to spearfishing on their respective websites. If you are lucky enough to be on one of these islands, then talk to the rangers to find out if you can spear there. The take home message here is that if you can’t find the information, talk to someone. Don’t just assume the it’s ok to go spearfishing. You could end up with a nasty fine or with your gear impounded.

Next Issue

So that pretty well sums up the rules and regulations around where your can spearfish or at least should give you some idea of where to find the information. I know it’s a lot, but you only have to check out your sites once and you will get to know your local area. In the next part of this guide I will cover what you can/can’t fish for. Remember, there is no catch and release in spearfishing. If you don’t know what it is, DON’T shoot it. I’ll cover where to find information on protected species and suggest some easy species to get started on and move on to some good sustainable fish species.

Octlantis

Photo credit: Kylie Brown

Below the clear blue waters of Jervis Bay, a gloomy octopus creeps along the sand foraging on the abundant scallops and hunting crabs when she can locate them. Her soft body is vulnerable to all sorts of predators, but she is a master of disguise, and can jet away in an inky instant as a last resort if she needs to. She is a long way from the safety of her den, but these are good hunting grounds and the risk is usually worth the reward. Today however, she spies a large shadow cruising along in the distance. Her skin morphs to resemble the colour and texture of seaweed as she attempts to creep away. The shadow approaches. A wobbegong shark – homing in on the minute electrical signals given off by the involuntary beating of the octopuses’ hearts (she has 3). No matter how good her camouflage is, the shark knows she is here somewhere and circles closer. Too close for comfort now, the octopus flees using her siphon to jet away. The shark, reacting to the sudden movement, gives chase. The octopus knows that she can’t outrun the shark. She must find cover. She ejects a cloud of ink into the water to cover her next dash. This buys her a second but the shark, highly alert now, knows she is here. She inks again and makes another panicked dash. She sees an irregularity in the otherwise ubiquitously sandy bottom and jets toward it. A small rocky outcrop with some kelp growing on it. Shelter. As she dives for cover under the kelp fronds, she sees a crack between the two boulders that make up this tiny oasis. The crack is only a few centimetres wide, but her body is soft and malleable and she knows that the shark will not be able to get to her in there. The shark soars over the rocks. It knows there is food down there, but it can’t get to it right now. Better to continue its hunting elsewhere, it cruises off into the distance. After a while, sensing that it is safe to emerge, the octopus crawls out of the crevice. Having fled in such a hurry, she has no idea where her old den is and having expended so much energy, she needs to feed. The rocky outcrop is surrounded by scallops and mud arks. Hardly even moving from the safety of the crevice, she reaches out a tentacle and plucks a large scallop from the sand. She deftly pries the shell apart and feasts on the meat within. She drops the shell and reaches for another scallop…

Why is Octlantis special?

Photo credit: Kylie Brown

The gloomy octopus, Octopus tetricus, is usually thought of as a solitary animal. Two sites have now been discovered in Jervis Bay, Australia, where O. tetricus gathers in groups of up to 15 animals which are challenging that perception and revealing some interesting and previously unobserved behaviours.

The second site, dubbed ‘Octlantis’ was discovered last year and consists of three rocky outcrops around which the octopuses have built up an extensive bed of discarded shells and human garbage. The discarded shells have provided material for more octopuses to dig their burrows in the sand which they then stabilise using the shells.

Doughboy scallops, a favourite food for the resident octopuses. Photo credit: Kylie Brown

This second site is centred around natural objects whereas the first site (known as ‘Octopolis’) reported in 2012, was formed around an unknown man-made object. The discovery of the second ‘natural’ site shows that the nature of the object around which the octopuses can make their dens is not as important as other factors (e.g. access to an unlimited food source) for the formation of a large group of octopuses. Social interactions (e.g. mating, attempted mating, reaching, eviction, displays and signals) observed at both sites also points to the ability of these octopuses to change their social behaviour from solitary to group living when conditions allow.

Misinterpretation of the report

We published a site description and some behavioural observations earlier this year. Since publishing this article, both sites have been the subject of a number of news reports. The early reports were accurate accounts of our report and welcome coverage of these unique sites. However many later news articles have exaggerated what we reported with the word ‘city’ appearing in a number of headlines (a word not used anywhere in our report). We did not find (nor did we report) octopus cities. The journalistic flare no doubt stems from the nick-names given to the sites (Octopolis and Octlantis), but we did not report these names. The use of the term ‘ecosystem engineering’ from an earlier paper has also likely led to the claim of ‘engineering underwater cities’, though the authors (of the scientific report) used the term in the sense that the piles of discarded shells created by the resident octopuses had significantly altered the habitat.

Ecosystem engineering and ‘intent’

Ecosystem engineering benefited the octopuses, but has also increased the abundance of some fish species, compared to the nearby sandy areas. Photo credit: Kylie Brown

While the octopuses have modified their environment by ‘constructing’ the extensive shell-bed in which other octopuses have dug their dens, it is not clear whether this ‘construction’ is intentional or not. A city on the other hand is constructed cooperatively with the intent to provide a centre for living, business and entertainment, among other things. It is very likely that the ‘construction’ of the octopuses’ shell-bed is simply the result of individual octopuses bringing food back to their dens (a safe place to eat) and discarding the shells just outside. That is, it is the shell bed is likely the unintended result of individual behaviour. This idea of intent will be explored further in a new paper currently in press.

What’s next?

As previously mentioned, the complex social behaviour observed at both sites is unusual for this species, at least as far as we know. The costs and benefits (e.g. energy expenditure vs access to food) of these interactions is yet to be investigated and may help us to understand why the octopuses at these two sites choose to tolerate each other, rather than conforming to the solitary strategy employed by the majority of individuals of the species.

The hard substrate in the middle of the shell-bed, whether it be of man-made or natural origin, appears to have provided a nucleus for the initial settlement of octopuses who have then created an extended shell-bed. Why then do we not observe large groups of O. tetricus in other areas where a solid object has been placed in seemingly ecologically similar areas?

These questions and many others are of great interest to us and are currently being investigated. Watch this space.

 

Into the Storm

slide1

Earlier this year I presented some of my findings at the 2016 Australasian Society for the Study of Animal Behaviour Conference in Katoomba. These findinges were based on data collected over the last 2 years during which my field sites have been impacted by 2 cyclones. Below is an adaptation of the talk from the conference.

The Importance of Sociality

slide2There are lots of examples in nature of animals that form social groups. These species gain advantages and incur disadvantages from their social behaviour. For example an advantage might be better predator detection while foraging (known as the “many eyes” hypothesis) while a disadvantage could include higher rates of disease transmission. Studies suggest that the evolution and maintenance of sociality is likely to be influenced by environmental factors. Changes in the environment, like those caused by extreme weather events, are therefore likely to impact upon the social organisation of social species.

For social species, the balance between the advantages and disadvantages of sociality are vitally important in determining reproductive output, competitive ability, foraging success and survival, factors which can ultimately impact on a species’ ability to recover from a major impact.

The Study System

slide3My research focuses on the coral gobies at Lizard Island, Queensland. Coral gobies are small fish, approximately three to four centimeters in length and they spend their entire adult lives within the branches Acroporid corals (corals of the genus Acropora). They suffer high mortality outside of their corals, and as such rarely move between corals once they have established themselves. I have observed up to 16 species of coral goby at Lizard Island which range in social organisation from strictly pair-forming species (which I will refer to as ‘Asocial’ species) to highly social species which can be found in groups of 12 or more (the largest group I’ve found was over 20 individuals).

slide4During my studies, two cyclones have impacted my sites at Lizard Island which has been quite disruptive to my research, but has also presented a rare opportunity to gain an insight into the rarely studied effects of cyclones on social organisation. There is no doubt (unless you’re a cyclone skeptic) that cyclones cause severe damage to the physical structure of the reef. This destruction obviously has impacts on the abundance, diversity and distribution of reef species following the event. For example, obligate reef-dwelling species (species which depend on the structure of coral reefs for protection and food) tend to decrease in abundance while algal grazers tend to increase in abundance. However we know relatively little about how these events affect social structures of reef inhabitants which is a potential driver of the diversity and abundance patterns we observe. As I previously mentioned, social organisation is important in determining factors such as reproduction, foraging success and survival, all of which are critical for a species’ recovery from a major disturbance.

Methods and Results

slide5

We have been surveying sites around Lizard Island since 2014. During these surveys we search each Acroporid coral on our transects for coral gobies. We identify the gobies to species and count the number of individuals living within each coral head (which constitutes a group). We also identify the coral to species and measure it along three axes to estimate an average diameter. I’ve used average diameter in my research so that my findings are directly comparable to previous work which has used this measurement.

The next few slides show some graphs and conceptual diagrams in which I’ve tried to use consistent symbols which I’ll briefly explain. The yellow fish represent ‘asocial’ species (they’re actually pictures of Gobiodon axillaris, a strictly pair-forming species). The green fish represent the social species (these are pictures of G. erythrospilus which is often founds in groups of 3 or 4). I’ve used a little cyclone symbol with an arrow on the graphs to indicate when a cyclone affected the field sites.

slide6We found that social species decreased in group size following each cyclone while asocial species group size remained the same. This indicates that group size decreases observed in social species were unlikely due to direct mortality from the cyclones (otherwise we would have seen a corresponding drop in average group size in the asocial species as well). A year after the first cyclone, the social species had returned to their pre-cyclone group sizes (keep this point in mind as I’ll return to this in a minute). However, a year after the second cyclone the social species had not returned to pre-cyclone group sizes. This may indicate that multiple impacts have longer lasting effects on social organisation.

slide7

Unsurprisingly, we found that coral size had decreased significantly throughout the study. This was the case for for both social and asocial species. The last set of bars on this graph shows the corals that were uninhabited. I’ve included this to illustrate that corals that were uninhabited at the beginning of the study (darkest bar) were of a similar size to the corals that the gobies were inhabiting at the end of the study. This means that at the end of the study, gobies were cramming into small corals that they previously wouldn’t have inhabited.

Let’s return now to that point I made about the social species returning to pre-cyclone group sizes a year after the first cyclone. From the coral size graphs we can see that these larger groups were cramming into smaller corals than before the cyclone.

Why?

I might pause here for a second to explain the underlying mechanism of the hypotheses of social evolution which I have looked at in this study, the ‘ecological constraints’ and ‘benefits of philopatry’ hypotheses. For both of these hypotheses we need to consider the proposition that social groups arise because subordinate individuals make the decision to delay their dispersal (often at a considerable cost to their own reproductive opportunities). The question of why some individuals will delay or forgo their own reproductive opportunities in order to remain within a group is one of the fundamental questions of evolutionary ecology. There are of course other ideas about why social groups arise, but this idea of delayed dispersal is what I will focus on for this study. It is also important to note that these hypotheses are not mutually exclusive and often act together.  So why separate them out? Well, because each hypothesis contains its own set of testable parameters. These parameters can be used to create a statistical model which we test against the real data and we can determine which hypotheses best describe the observed social structure.

Ecological Constraints

slide8This hypothesis looks at ecological factors which might constrain dispersal from a territory such as a lack of available habitat or high predation pressure. In relation to my work, one of the reasons that the social gobies might have re-formed their large social groups in smaller corals could be that they were constrained by a lack of available habitat. i.e. Gobies displaced by the cyclone might have had no choice, but to move into a coral which already had a small group of fish living in it. In this case, we would expect to see that most of the corals would be inhabited because vacant corals would be quickly taken up by gobies dispersing from crowded corals.

Benefits of Philopatry

slide9This hypothesis looks at the idea that animals gain some benefit of remaining on a site that outweighs the benefits of dispersing. For example, the site might be of a high quality which improves the animal’s fitness to survive and reproduce. Dispersing from this site risks, losing this benefit, unless it can find a site which confers the same or better benefits. In my project, it is likely that there was a lot of variation in coral quality following the cyclone. While fish might have quickly moved into whatever shelter they could find, they might have realised later on that their coral was not very good (indicated by the green, algae covered coral in the diagram), and decided that it was more beneficial to vacate their low quality coral and move into a high quality coral (white coral in the diagram) with an existing group of fish. In this scenario, we would expect to find a lower proportion of inhabited corals than we would under the ecological constraints scenario as fish would have vacated low quality corals in favour of high quality corals.

slide10What we found was that after the cyclone, there was indeed a substantial drop in the proportion of inhabited corals. While this doesn’t definitively prove that benefits of philopatry are causing the observed social patterns, it does lend some support to the idea. There was also a drop in the proportion of inhabited corals for the asocial species, but it was not as substantial as that observed for social species. This likely due to a methodological ‘artefact’ which I won’t get into, but suffice to say, for social species, there is some support for benefits of philopatry playing a role in the observed social pattern following the first cyclone. Stay tuned for a more in-depth analysis of this data.

slide11So, in summary, the major findings of this study were that after a cyclone, social species reduced in group size but asocial species did not. A year later social species had returned to their pre-cyclone group sizes, but in smaller corals. There is some evidence that benefits of philopatry are contributing to this pattern. The fact that asocial species did not alter their social organisation could indicate that the asocial strategy is either more robust to such an impact or that it is less flexible. Unfortunately, my surveys were not designed to examine patterns in abundance and I can’t really say whether either strategy is better or worse for recovery following a cyclone. This would be an interesting avenue for further research. Following a second cyclone, social species again decreased in group size, but did not return to pre-cyclone levels another year down the track. This might be because multiple impacts have longer lasting effects on social structure or because corals had reduced to such a small size that they were not capable of supporting larger groups.

Social organisation in social species is influential  in determining survival. The effects of cyclones on social structures has received little attention thus far in the scientific literature. While my research raises many questions, I hope that it can provide a foundation to build upon and move toward  a better understanding of how severe weather events might impact upon social organisation.

I would like to thank my supervisors and field assistants who have contributed to this work. Also a shout out to the Hermon Slade Foundation for funding this research and  the Lizard Island Research Station for accommodating us.

A plea to new spearo’s

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A great weekend diving with friends was somewhat tarnished by the actions of a naive spearfisher. We were unfortunate to witness a spearo enter the water in a sanctuary zone (no-take zone) and spear a blue wrasse, a protected species in NSW.

Spearfishing is a great way to get some fish into your diet. It can be a great challenge learning to freedive and learning to observe fish behaviour. That being said, there are no throw backs with spearfishing. Which is why I implore people new to the sport to know where you can fish and what species are ok to target. Do not pull that trigger unless you are 100% certain that the fish is of legal size and not protected. The fisheries rules are in place to help sustain our fish populations so that everyone can continue to enjoy our oceans.

Getting started can be daunting. It might seem like there are a lot of species to learn and there are. I would recommend tagging along with someone more experienced until you get to know your local fish. Join a spearfishing forum – there are often people looking for buddies. Failing that, get out and go freediving without the spear and look up the fish you see. In only a few dives you will quickly learn the common fish at your local sites. If you really want to get straight into it, consider deciding on a specific species to target before you even get in the water. Failing all of this, you can follow 1 simple rule: If you don’t know what it is, don’t shoot it. 

Some useful websites:

DPI Fishing rules – http://www.dpi.nsw.gov.au/fishing/recreational/fishing-rules-and-regs/saltwater-bag-and-size-limits

Marine protected areas – http://www.dpi.nsw.gov.au/fishing/marine-protected-areas

Spearfishing forum – http://www.spearfishing.com.au/sf-forum/

The Rapture of the Deep

DCIM100GOPRODeep diving is something that I am passionate about – especially if it involves a shipwreck. It is a chance for me to push my skills, training and equipment and to explore some of the lesser dived or known sites. However this comes at a considerably higher risk which involves specialised training and equipment to manage safely. One of these risks is Nitrogen Narcosis – aka “the rapture of the deep”. Not a lot is known about the causes of nitrogen narcosis, but it is a narcotic effect brought on by the increased partial pressure of nitrogen in the breathing gas at depth. The threshold for nitrogen narcosis is different for each diver and can even vary dive-to-dive within a diver, depending on many factors. I usually enjoy getting a little “narc’d”. It can be quite euphoric and enjoyable if managed well. Nitrogen narcosis itself is not dangerous, unlike decompression illness, and there are no long lasting effects – no nasty hangovers. What can be dangerous though is the impaired actions of the diver experiencing euphoria. It’s essentially diving drunk. Nitrogen narcosis, like other narcotics can also present as paranoia and confusion which can lead to panic. Bad news in any depth of water. Thinking about these effects, I thought I’d share a story I wrote about a dive many years ago where I was overcome by narcosis paranoia in the hope that others can learn from my bad experience. This dive was a huge learning experience for me and still serves as a source of healthy anxiety before a deep dive. Nitrogen narcosis is not something that can be (nor should be) avoided, but it is certainly something to be aware of.

Before I get into the story, I should also make a quick note about solo diving. This practice is often frowned upon in diving circles and I do agree that diving with a buddy significantly reduces many risks associated with diving. However, I also believe that with proper training and additional equipment, many of these risks can be minimised and solo diving can be conducted reasonably safely. The training that I have done to enable me to dive outside the recreational limits had a special focus on redundant equipment and self reliance in emergency situations. I personally find solo diving to be quite relaxing and enjoyable, but only because I take the necessary precautions when I do it (which isn’t often).

When 3 things go wrong…

“If you turn right when you get to the anchor you’ll see the boiler. Then if you go left from there, you’ll get to the stern section” said my buddy.

“No worries. Too easy”. I think to my self.

There are some days when you really should just stay in bed. I was gearing up to dive a wreck off Sydney. It was one of those magic days on the water, with the sun newly risen and barely a whisper of a breeze to ruffle the smooth surface of the ocean. Unfortunately this magic had been marred by the realisation on the trip out that I’d left the undergarment for my dry suit laying on the back seat of my car. Idiot! This was to be the least of my troubles on this dive. As I was gearing up, to my horror I discovered that my fins were no where to be seen. They too were laying in the boot of the car along with my ankle weights. The ankle weights didn’t really concern me, but without my fins I was resigned to being the boat boy. Shit! how could I forget my fins! The undergarment and ankle weights were no big deal, I could get by without them, but my fins! You Idiot! I cursed my self again.

My buddy has said on many occasions “when you have 3 things go wrong on a dive, any 3 things at all, call it off”. Hmmmm, fins, ankle wights, undergarment…. I should have taken that advice.

The two others on board rolled over the side and descended onto the wreck 50 m below. I watched them disappear into the inky blue depths. 20 minutes later my buddy reappeared on the surface. He was diving in a wetsuit and was getting cold so had called his dive short. He climbed back on board raving about the excellent visibility and the fish life. He suggested I take his fins and go check out the wreck. It didn’t take much to talk me into it, although I could hear his words (spoken to me so many times) going through my head “when 3 things go wrong….”. But I couldn’t resist. I had gotten up early and made the trip out here and I was grateful to him for the offer of his fins, giving me the opportunity to explore this wreck that I’d heard so much about.

So I turned on the air for my two back mounted tanks, checked my gauges and climbed into my harness. As I was attaching my stage tank (a 3rd tank containing a Nitrox mix to reduce the ascent time) my buddy described the layout of the wreck to me.

“If you turn right when you get to the anchor you’ll see the boiler. Then if you go left from there, you’ll get to the stern section”.

I was so excited by this stage as this was my first time on this wreck and the conditions couldn’t have been better.

“What bottom time are you going to do?” He asked me.

“I’ll just do 10 minutes” I replied, feeling safe in the knowledge that I’d previously planned a 20 minute bottom time with breathing gas to spare.

I donned my buddies fins, went through my final checks, rolled over the side and kicked below the surface to the anchor line.

Breathe in breathe out…. slow, even breaths. Equalize. The particles suspended in the water whiz past me as I descend. I’m dropping fast. Breathe in, breathe out, equalize. Check instruments: depth – 12 m, dive time – 0:00, air – 223 bar. Every thing looks good. I feel great! I love this part. There is nothing around me. The only reference is the anchor line in front of me, disappearing into oblivion. I feel like I’m in free fall.

The visibility at this depth is only 5 m at best. My descent continues. 15 m… 22 m… 25 m… The visibility opens up. I can just make out the wreck below me sitting in 50 m of water. The gunk in the water above me partially blocks out the sunlight. I turn on my torch, more for comfort than anything else. I’m breathing a little harder now with the increased pressure so I adjust the resistance on my reg and add some more air to my dry suit to slow my descent. as I pass through 30 m depth I’m still dropping fast so I add some air to my BC to slow my descent.

Instrument check: depth – 48m, dive time – 0:02, air – 204 bar. As I arrive at the bottom, I try to unclip my reel from my harness. My fingers are clumsy, I must be narc’d but I still feel fine. I get my reel free and manage to tie onto the anchor line. I take a couple of seconds to catch my breath and gather my senses. Breathe in… breathe out… Wow! I am narc’d! I can’t concentrate…. better check my gauges: 0:05 dive time. What happened to those 3 minutes! This is fantastic! The vis is at least 30 m! 3 huge trevally cruise past me glinting bronze in my torch light. I watch them disappear into the distance. I’m surrounded by wreckage covered with tiny pink, purple and white bryozoans. Orange and yellow sponges fight for space with iridescent algaes. A school of pomfret, glowing golden in my torch light, cascade over parts of the wreck. I’m loving it!

Ok, what was I doing?…. Turn right from the anchor…. Right or left? No it was definitely right…. Which way is that? Ok concentrate now… this is my right hand… turn that way. I see the edge of the debris field and sand…. Where is the boiler? I keep turning. There’s the anchor…. Ok, I’ve turned right around. maybe it was left…. Ok turn left…. Wreckage… Sand… Anchor. I’ve turned around again…. where is that boiler? it was definately “turn right from the anchor”…. Ok, calm down, breathe. Should I bail out? I’m really really narc’d and I feel like I’m really pushing my abilities. No I’m ok, I’m well trained, I’m using familiar equipment (apart from the fins), my skills are up to scratch and I have heaps of air… I can handle this situation. Stop, breathe, think and act. Breathe in….breathe out. Think: “turn right from the anchor…” Act. Ok…. turn right. Ok I see a shadow out on the sand…. Is that the boiler? All the way out there? Ok… Start swimming…. It’s hard work…. Bugger that. I’m not swimming out there. Turn around… Which way?… Oh yeah, that’s right, it won’t matter.

I turn around and reel my way back to the anchor. I’m so narc’d. I can’t think. Calm down…. Breathe…. Check instruments: dive time 0:08 minutes. damn! I’ve wasted most of my bottom time. Air – 182 bar. I can’t think straight.

I close my eyes to try to gather my thoughts. Breathe in… Breathe out… Ok…. I’m on the edge of the debris field. I’ll just follow the sand line for a little bit. Which way? There’s a slight current… I’ll just drift along with that…. No wait!… I tell my students not to do that in the open water course… But I only have 2 minutes left. I’ll just drift a little way, then turn around. It’ll be fine.

I move along the wreck with the current. There are some beautiful little gorgonian fans, and some little pink bryozoans. Three juvenile blue wrass scull along beside me…. This isn’t so bad… A little leather jacket moves out of my way. Wow! this is a beautiful wreck! There are scattered deck plates and beams all around me. I wish I could have found that boiler or the stern section. Ah well next time… Oh shit! what’s my bottom time? 0:10! Shit! Turn around. I swim into the current. It’s not strong, but I have to work harder. I can feel my breathing rate increase with the extra effort. I reel in my line as I swim back to the anchor.

Back at the anchor. Instrument check: dive time – 0:11 minutes, air – 156 bar. My computer tells me that I require a 4 minute stop at 6 m with a total ascent time of 13 minutes. It’s ok, I have plenty of air and a 40% nitrox mix in my stage tank. Ok… relax… I try to detatch my line from the anchor chain, but my fingers just won’t work the way I tell them to. Finally the line comes free (I was so close to cutting it). I secure the reel to my harness and begin my ascent. Dive time – 0:14. Shit! I stayed way too long. I’m ok, I’ve got plenty of air left. I make my way up the anchor line. not too fast….dump air….breathe in breathe out. Up I go… at 25 m (the safe operating depth for a 40% nitrox mix) I reach for the reg on my stage tank but unbeknownst to me, the hose is caught on the buckle. I pull at the reg, but it wont come free. I’m still going up… dump air…. breathe…. I’m thinking more clearly now. Ok stop… Breathe… Think: “why won’t the reg come free?…. It’s caught on something”… Act: follow the hose with my hand. Ok, it’s caught under the buckle here. Ok, there it goes. I pull the reg free and start to breathe my nitrox mix. Instrument check: Dive time – 0:18 minutes, gas – 200 bar, 10 minute stop now required at 6 m. I make the gas switch on my computer. it re-calculates my ascent profile taking into account the new gas mixture I’m now breathing. Dive computers are such wonderful things! 1 minute of decompression now required at 6 m, total ascent time, 7 minutes. I slowly make my way to my 6 m stop and wait for 1 minute. Up to 3 m for just 5 minutes (oh how I love nitrox).

Hanging on the anchor line at 3 m I have time to contemplate the dive. I was out of my depth (excuse the pun). It all started out wrong. I feel lucky to be back near the surface. Things could have really gone wrong down there. Well, actually, maybe I’m not lucky, per se. When I knew I was getting into trouble, my training kicked in: Stop, breathe, think and act. And I was able to gather my self sufficiently to be able to get back safely. Nevertheless, I’ve learnt some valuable lessons from this dive. I should have bailed out when I felt the narcosis become overwhelming. Always start the dive swimming into the current. Practice practice practice with your equipment so that muscle memory can relieve some of the task loading on your brain at depth. And especially “When 3 things go wrong…”

Make your assignment marker happy

The dreaded red pen.

The dreaded red pen. An example of a very frustrated marker. I hope my feedback was a little less personal (this is NOT a picture of my marking). 

Recently I’ve been marking for some second and third year biology classes. I’ve been a little shocked at the quality of the work the students have been presenting. I found myself wondering whether I was marking them too hard? However, I soon came to the conclusion that this was not the case.

One of the classes is a third year class and some of these students are on the cusp of completing a Bachelor of Science without knowing whether to use “two”, “to” or “too”. It’s a scary thought. I would like to think that these students wouldn’t be able to complete their degrees with such appalling spelling and grammar, but let’s face it, they’ve made it through to the final semester of their undergraduate degrees in this fashion. As a marker of a third year subject, I should be committing my time to marking the content and assessing a student’s understanding of the subject matter rather than correcting basic spelling mistakes.

As scientists, good writing skills are essential. It’s what we do. When all is said and done, the time spent writing vastly outweighs the time spent on experimental design and data collection. Writing is how we convey our research (with the odd presentation thrown in for good measure) to the scientific community, decision makers and the broader public. Unfortunately, most of us (myself included) are not born writers. It is a skill that is developed through reading and especially through writing.

Good writing starts with the basics (spelling, grammar, presentation) and this is where I am finding that a lot of students are falling short. As a marker, I’ve found myself writing the same comments on these basic concepts over and over and over and over again, which makes me miserable.

It is such a delight to find that one paper among it all that just nails the basics. These few papers are the ones that stand out to markers and (somewhat unfairly) receive disproportionately higher marks. i.e. if I mark two papers with essentially the same content, the one with the good spelling, grammar and presentation is going to get the higher marks every time.

These small things matter. Not only for undergraduate assignments, but for report writing, grant applications and manuscripts for peer reviewed journals, which these students will face in the workforce. Then it is not just the grumpy marker that they’ll have to face. It will be the supervisor, the reviewer, and the question of continued employment that they will be contending with.

This being the case, I’ve started developing a report writing guide for my students. It is still very much a work in progress but I would welcome any feedback on it. It is aimed at science students, so some of the sections on presentation may not be applicable in other disciplines.

If you are a teacher, examiner or marker and you find this guide helpful, please feel free to share it with your students/friends in the interest of promoting good writing skills. If you are a science student, I hope this guide helps to boost your marks and improve the mood of your marker. Please let me know if there are things that you struggle with that are not included in the guide. If you are one of my students I hope you read this guide and apply it to your next assignment. I look forward to reading them and awarding some much higher marks for your hard work.

Report writing tips (download)

 

State of fear: what should we do about sharks in New South Wales?

Jane Williamson

Sharks have long been a symbol of the terror of the deep seas and a source of trepidation among Australian beachgoers. But a recent cluster of dangerous encounters with sharks in New South Wales has raised new concerns among the public and sparked fresh calls for culls.

Fears of more casualties are also changing the way our beaches are being used. Some high schools have reportedly cancelled their surf programs, and several surf lifesaving clubs recently announced that they will seek other venues for “Little Nipper” training.

So what’s actually happening with the sharks?

Shark attacks or shark bites?

Negative interactions between sharks and people can range from light (small lacerations and stitches required) to severe (large pieces of flesh removed, including limbs).

All are routinely termed “attacks”, but as this emotive word conjures up a perception of maliciousness on the shark’s behalf it is not a very useful description. There is a recent move to rename shark attacks as “shark bites”, in the same way that injuries from aggressive dogs on humans are documented, thus lessening the incorrect perception that all interactions with sharks are fatal.

Due to their public interest, there are good data sets on negative interactions with sharks in both Australia and globally that span centuries. Comprehensive data on shark bites, including those in NSW, are collected and compiled in the publicly available Australian Shark Attack File (ASAF), which was established in 1984 and is held at Taronga Zoo.

ASAF data and associated publications do show that shark bites have increased over the past couple of decades, from an average of 6.5 incidents annually from 1990 to 2000, to 15 incidents per year since 2000.

Interestingly, however, while the number of shark bites has recently increased, the number of deaths resulting from the bites remains consistently low (an average of 1.1 people per year over the past 20 years).

Why are fatalities from sharks not increasing in proportion with the increase in shark bites? If sharks were the premeditated killing machines portrayed by the media and entertainment industries, why do most negative shark-human interactions involve only one bite and not the victim being consumed?

Feeding habits

Answers lie in the way that sharks feed. Sharks are apex predators that actively hunt their prey, which can include fish, seals and whales. But they are also opportunistic scavengers that feed on dying or dead organisms, as do terrestrial predators such as bears and lions.

It is important to understand this because it means that sharks are not always the hunters they are painted as. A surfer in a wetsuit paddling on a board could be mistaken for sick or dead prey, floating on the water. The shark may give an exploratory bite to assess. Unfortunately such exploratory bites can remove substantial tissue and even limbs in humans, particularly if the shark is over two metres in length, and may thus be fatal.

Data from ASAF support the concept that sharks are not actively hunting humans as prey, and that a bite is more often a “mistake” by the shark. The vast majority of bites occur on a victim’s extremities (legs, arms), consistent with exploratory bites by scavenging sharks. The shark usually disappears after the initial bite. There are no accounts of a person also being bitten when coming to the aid of a bitten victim in the water.

More people, more encounters

While the number of negative interactions with sharks has risen this year, there have been previous clusters of interactions in ASAF data. A peak of 74 incidents was documented in the 1930s. Considering the method of reporting at the time, it is highly likely that this number was greater.

While it is easy to assume that today’s increase in negative shark-human interactions is directly related to an increase in the number of aggressive sharks in the vicinity, there are other hypotheses that can explain this pattern. John West, the curator of ASAF explains that more contact between sharks and people has also resulted from an increase in the number of people and how they use the beach.

The number of incidents and their locations coincide with an increase in the number of people residing in rural coastal areas, particularly in northern NSW. There has also been a steady increase in the use of beaches and water activities over past decades, which has resulted in more people being in the water.

People have also extended their time in the water, with an increase in the use of wetsuits. Methods for reporting negative shark interactions have also improved. All such reported interactions attract substantial media attention in recent times, leading to the perception of proportionally more interactions than actually occur.

It is also highly probable that the behaviour of the sharks may have changed and not the number of sharks in the water. Sharks are known to come into shore to follow baitfish, which have been prevalent in the shallow waters of beaches this year. It is difficult to know the probability of this without rigorous scientific data that track the patterns of movements of the sharks.

To kill, or not to kill

Following the recent spate of bites this year, controversy exists as to whether beaches in northern NSW should be meshed – which has been known to indiscriminately kill sharks. However, negative shark interactions continue to occur in beaches from Newcastle to Wollongong that are periodically meshed by the Shark Meshing (Bather Protection) Program.

Since 2005, shark bites have occurred at 13 of the 51 meshed beaches. This should not be too surprising because the nets are only 150 m long and 6 m high, allowing marine organisms to swim over, under and around them. Shark nets are not continuous curtains of net that completely enclose areas for swimming, as in the case of the stinger nets found in northern Queensland. Moreover, they are deployed for only part of the year.

But experience from Western Australia shows that shark culls also do not work. Instead, NSW Premier Mike Baird has announced an A$250,000 shark tagging and surveillance program alongside an international “shark summit” to be held this month.

Baird’s more measured and rational approach to beach safety should be welcomed as a valuable addition to a debate so often driven by fear.

Jane Williamson, Associate Professor in Marine Ecology

This article was originally published on The Conversation. Read the original article.

Shark!

Did that get your attention?

There has been a lot of media attention surrounding sharks recently, starting with that terrifying footage of Mick Fanning and a number of incidents on the NSW north coast. Following on from these incidents there have been calls from a very vocal minority of ocean users to ramp up efforts in shark control measures. It should come as no surprise that I don’t support lethal methods of shark control. As far as I’m concerned there are much bigger risks in life than the threat of being bitten by a shark. If we wish to enjoy the ocean we should know the risks and accept that we share this wonderful environment with these apex predators. However, with all of the media hype, it’s easy to forget that we also share the ocean with some other amazing animals, which is what I though I’d share today.

The beauty of the ocean never ceases to amaze me.

A picture tells a thousand words Jan – Feb Lizard Island trip

I was joined by my sister, Kaz (author of the Madagascan Adventure series) on my latest field trip to Lizard Island. We repeated the surveys that Kylie, Grant and I had conducted last time and ran an experiment to investigate whether a subordinate fish would decide to move out when exposed to an adjacent coral of varying size and with different numbers of fish already residing in it.  I hope you enjoy this visual expose of our time there.

Life at Lizard

The Experiment

For a brief description of the experiment we ran see here.

Day Reef trip

We were honoured to be invited by Anne, Lyle and Alex for a trip out to Day Reef on our day off. It was meant to be a dry day for us, but we were willing to make the sacrifice!