Supporting genetic analysis of protected fish species

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POP2015-07: Supporting genetic analysis of protected fish species 2015/16 (PDF, 869K)

Summary

Nine fish species are currently protected in New Zealand fisheries waters (white shark, basking shark, whale shark, oceanic whitetip shark, deepwater nurse shark, spinetail devilray, giant manta ray, spotted black grouper and giant grouper). All nine species have low productivity, which in combination with fisheries threats make them vulnerable to over-exploitation.

The wide distributions of most species, and the broad expanses of ocean between New Zealand and other population centres of all nine species, raise the possibility that some or all of them may have multiple, isolated, geographic populations.

Understanding population structure is important for managing the New Zealand populations of these nine species. Even though the species are protected within the New Zealand EEZ, they may be subjected to fishing and environmental impacts elsewhere if they form part of more extensive geographic populations.

NIWA has been collecting tissue samples from white shark since 1991, from basking shark since 1997, and from spinetail devilray since 2013. These samples were used to form the nucleus of a new library of protected species tissue samples, and a database of worldwide tissue samples of New Zealand's protected fish species was compiled.

The database contains good sample sizes of white shark (N=102) and basking shark (N=56) but small or no samples of the remaining seven species. Few of the tissues are held in the NIWA repository, with most being held elsewhere.

Genetic studies on the nine protected species found during a literature review and correspondence with geneticists worldwide are summarised and reviewed. Worldwide population genetics studies have been completed for white shark, basking shark, whale shark and spinetail devilray, although no studies on whale shark have included New Zealand material. The remaining species have been studied in only part of their range or not at all.

Most of the species covered in this review have widespread, often global, distributions but the samples sizes of many studies were limited. A key priority is to continue to gather samples and make them available to other researchers to complement samples collected from other locations. The ability to detect population hierarchies will enable reproductive units to be more clearly defined and improve the setting of conservation priorities.

Publication information

Francis M. & Ritchie, P. 2016. Genetic studies of New Zealand's protected fish species 2015/16. Report prepared by NIWA and Victoria University of Wellington for the New Zealand Department of Conservation, Wellington. 33p.