No safety net for sea lions in fisheries – expert

Devices installed in squid trawling nets to prevent sea lion bycatch lack evidence that they actually prevent sea lion deaths, according to an expert.

This week Primary Industries Minister David Carter released a management decision for a key squid fishery near the Auckland Islands, claiming that it reflects new research showing that devices that reduce unintentional sea lion deaths in trawling nets are working.

In the release, Mr Carter stated: “Improved scientific research shows Sea Lion Exclusion Devices (SLEDs), that enable sea lions accidentally caught in fishing gear to escape, are working.

However, a researcher studying this issue disputes this claim and expresses concern over the likely impact on sea lion populations.

Dr Bruce Robertson, Senior Lecturer in Zoology at the University of Otago comments:

“This is a dangerously optimistic decision. The statement that sea lion exclusion devices (SLEDs) are highly efficient is not based on scientific research, as there is no evidence that dead sea lions are retained in trawl nets by SLEDs. With our current state of knowledge, the decline in bycatch could just as likely be explained by changes to SLEDs now unintentionally allowing dead sea lions to be ejected from nets and hence not recorded. A 2007 review of SLED compliance — referenced as evidence that SLEDs are working as intended — only shows that all SLEDs have the same dimensions and says nothing about whether they work as intended by the designer (i.e. allow live sea lions out and retain the dead ones).

“The scientific experiments have not been done to demonstrate SLED efficiency, so pointing to a decline in sea lion bycatch at this stage is deceptive and misleading. This claim is like a car designer saying the new model is 100% safer than the last one without ever doing any crash testing.

“This decision could have a major impact on sea lion numbers – based on previous modelled catch rates (5.65 sea lions killed per 100 tows) there could be over 250 sea lions killed if 4700 tows are undertaken in the fishery.  It is worth noting that not only is the 4700 tows bad news for sea lions, it is beyond the total allowable catch for squid in the squid fishery.”