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

 

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