In this paper we share the New Zealand experience to reduce the observed New Zealand Sea Lion bycatch in the Southern Squid Fisheries. Some of the experience gained during the design, development and implementation of the marine mammal mitigation devices in this fishery could be explored for relevance to the CCAMLR krill fisheries. The New Zealand Sea Lion/Pakake/Whakahao (Phocarctos hookeri) is considered the rarest sea lion species globally and classified as Endangered (IUCN A4bd). A Threat Management Plan (TMP) has been in place since 2017 to mitigate threats to this species. The Southern Squid Fishery (SQU6T) uses Sea Lion Exclusion Devices (SLEDs) to mitigate incidental fisheries mortality of sea lions and are required by the TMP.
The SLED consists of a section metal grid at 45 degrees inserted between the lengthener and codend of the trawl net, designed to direct sea lions to an escape hole in the top of the net. The use of SLEDs on fishing vessels is required on all tows in SQU6T, is supported by at least 90% observer coverage across all tows in the squid fishery, and the fishery has an annual fisheries-related Sea Lion mortality limit of 52. Fisheries-related mortality is estimated using observed sea lion captures multiplied by a cryptic mortality factor of 1.3. The success of the SLED evolved from the efforts to test different design options and identify potential improvements before its full implementation. Fisheries observers record sea lion captures and review that the SLEDs are compliant with design specifications and deployment requirements. The recognition of cryptic mortality added increased precaution to the estimates of fishing-related mortality, and hence the potential impacts of the fishery on the New Zealand Sea Lion population.
The krill fishery in the CCAMLR Convention Area has significant differences with the NZ Southern Squid (SQU6T) trawl fishery: in its operation, design of fishing gear, and species of marine mammals captured. The New Zealand experience in the design and implementation of bycatch mitigation devices may contribute to research on mitigation measures to reduce marine mammal bycatch in the CCAMLR Convention Area. We propose that WG-IMAF recommend:
- Bycatch mitigation devices are further improved and trialled in CCAMLR krill fisheries.
- Estimates of cryptic mortality rates are considered when bycatch mitigation devices are used.
- Where mitigation devices are used, mitigation device standardisation and certification processes are developed.
- A minimum rate for scientific observer coverage is developed to support the evaluation of marine mammal bycatch mitigation methods.