Sharks

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.

WA Shark Hazard Mitigation Program proposal summary

Clear-Tiger-Shark-Picture-In-Deep-Blue-Sea

The good

  • Limited area
  • Limited time
  • No nets = less bycatch
  • High release rates

The bad

  • 26% of total captures from the trial program were within the specified target range
  • Bycatch of “non-target” shark species
  • No estimation of tiger shark population

The ugly

  • Catch of female tiger sharks significantly higher than male tiger sharks
  • No evidence to suggest that a drum lining program will achieve the policy objective of improving ocean safety

 Proposal summary

Metro and South West Marine Managed Areas. Source: http://gallery.mailchimp.com/26c3400f39a2a193da8d06aae/files/5a5f625a-6a30-4a52-8535-00af8115542b.pdf

Metro and South West Marine Managed Areas. Source: Western Australian Shark Hazard Mitigation Drum Line Program 2014-17 – Public Environmental Review

The proposal is to place up to 60 baited drum lines approximately 1 km offshore from selected high use swimming beaches from 15 November to 30 April each year. The “target species” for the program are great white sharks, tiger sharks and bull sharks greater then 3 m in total length (from the tip of the snout to the furthest tip of the tail). These drum lines will not be placed in any marine park zones. A further 12 baited drum lines may be temporarily deployed at any place (within WA waters) at any time in response to identified shark threats or incidents. It is proposed that these temporary drum lines will be allowed to be placed in marine protected areas after consultation with the Department of Fisheries Operations Manager and the Department of Parks and Wildlife.

 Trial program

Drum line

Example drum line configurations. Source: Western Australian Shark Hazard Mitigation Drum Line Program 2014-17 – Public Environmental Review

The WA Government ran a trial baited drum line program from 25 January 2014 to 30 April 2014. During this period, 163 tiger sharks were caught, the majority of which were female and less than 3 m in total length. 99 were released alive while 64 either died or were destroyed as they were over 3 m in length. 5 short fin mako sharks were also captured of which only 1 was released alive. 1 dusky shark, 1 spinner shark and 1 bull shark were also captured and released alive. 7 rays were captured and released. No great white sharks were captured.

3 tiger sharks were fitted with acoustic tags. one of these is confirmed to have died shortly after release. Another was picked up by a reciever 30 min after release and the state of the third shark is unknown.

Risk assessment

An environmental risk assessment has been conducted for the proposal. It found that there were either no or negligible risks to the population status of two of the three target species, all of the non-target species and the broader ecosystem. The program was considered to pose a low risk to the population status of tiger sharks.

Issues with proposal

Although the environmental risk assessment appears to be quite thorough, there is no population estimate for tiger sharks, which form the vast majority of catch from this program. There is also no estimate for post release mortality. Compared to commercial and recreational catch estimates, the expected mortality of tiger sharks from this program is quite low, bit it should be kept in mind that the number of tiger sharks killed by this program is additive to the fishing mortality of sharks. Additionally, there is no estimate of the mortality to tiger sharks from illegal fishing. Despite this, the program was considered to only represent a low risk to the population status of tiger sharks.

The proposal touts the trial program as a success. However, the stated target species for the program are great white sharks, tiger sharks and bull sharks greater than 3 m in total length. 163 tiger sharks were captured of which 47 (28.8%) were greater than 3 m  total length. No great white sharks were captured. A single bull shark of 1.97 m total length was captured. So of 180 total captures (including bycatch), 47 were within the target range.

The program was considered not to pose a threat to any matters of national environmental significance (MNES), primarily because of the low environmental footprint (i.e. limited area and time). However, the impact to world heritage sites, such as the Ningaloo Coast and Shark Bay, which are located away from the impact area did not appear to be well considered. Although the proposed location of the baited drum lines is at the southern extent of the tiger shark’s range, they are known to be highly migratory. The program is expected to capture approximately 300 tiger sharks in each season. Given that there are no estimates for post capture mortality and no estimate of the current population of tiger sharks in the region, the impact that this program may pose to world heritage sites in the wider area are unknown.

Conclusion

tigershark2On paper this program appears to be quite well thought out and is backed up by an environmental risk assessment. It is commendable that the WA Government is investing a considerable amount of funding into research initiatives and programs such as surf lifesaving. However, I am still ethically opposed to the proposal. I know it might sound hypocritical for me to write this, living in a state which has had a beach meshing program operating since the 1930’s, but I think the NSW program stinks too. In comparison, the WA proposal seems to be quite palatable.

However, the very basis for these programs is to make people feel safer about swimming at the beach. Shark bites, while terrifying and tragic for those involved, are incredibly rare events. In 2013 there were 10 unprovoked shark attacks in Australia, according to the Australian Shark Attack File. Of these 10 attacks, 2 were fatal. The Royal Life Saving Society of Australia reports that 110 people drowned at beach and ocean or harbour locations in Australia in 2013. According to the Department of Infrastructure and Regional Development, there were 1193 road deaths in Australia in 2013. I could go on and on about things that are more likely to kill you than sharks, but there are already a plethora of websites and amusing memes circulating which adequately cover that topic. The point being that the WA Government is proposing to initiate a lethal program with little studied impacts to the wider ecosystem to address an issue that is (forgive the pun) a drop in the ocean.

Ironically, I think the NSW Government has summed it up nicely on their Primefact page about the Bather Protection Program: “While shark attacks are exceptionally rare events, there is a risk inherent in swimming in any waterway. The only way that you can 100% guarantee you will not have a shark encounter is not to go into the water”.

If you would like more detail about this proposal, there are some useful links below or as always, please feel free to contact me using the contact form below. Again I would like to encourage people to take a moment to write a submission to the EPA on this proposal. Feel free to use any of the details from this post, but I would appreciate it if you didn’t just copy and paste.

Links

Public Environmental Review – Western Australian Shark Hazard Mitigation Drum Line Program 2014-2017

Support our Sharks – Action Alert: Stop the WA shark cull

Australian Government – information on world heritage sites

Predicting ecological consequences of marine top predator declines

Southern Fried Science – 24 species of sharks that have killed fewer people than Jack Bauer on 24

Contact

 

Western Australian Shark Hazard Mitigation Drum Line Program

White_shark

The Environmental Protection Agency in Western Australian are now accepting submissions for public comment on the proposed WA Shark Hazard Mitigation Drum Line Program 2014 – 2017.

I would urge people to have a look at the documentation here and to make a submission here. On the face of it, I am personally opposed to the idea for the following reasons:

  1. I like sharks.
  2. Many species of non-target sharks are captured on drum lines.
  3. Other forms of marine life such as whales and turtles could become entangled.
  4. Great White Sharks, one of the “target” species, are listed as vulnerable under Western Australia’s legislation (Wildlife Conservation Act 1950 (Western Australia)). Great White Sharks are also listed as vulnerable under national legislation (Environment Protection and Biodiversity Conservation Act 1999). 
  5. Shark control programs such as those implemented in NSW and Qld have not significantly reduced shark attacks.
  6. Many, many more people die at the beach from drowning than shark attacks (don’t get me started on things that kill more people than sharks).

But don’t take my word for it. At least read the executive summary for the program and make up your own mind. Over the next couple of weeks, while the submission period is open, I’ll be reading through the rest of the documentation  and some other material. I’ll try to post the juicy bits on here for you. Please take this opportunity and let the WA Government know what you think of the program.

Useful links

Conversation article on the WA shark mitigation program

CSIRO publication on shark attack patterns

My personal favourite, the Great White Shark Song.