An independent panel of three international experts has concluded a review of the scientific information used to guide the management of New Zealand’s eel fisheries, particularly longfin eels. They found that although longfin eel numbers declined up to the late 2000s, their numbers appear to have stabilised in recent years. One of their recommendations is that a comprehensive assessment is undertaken that includes fisheries and non-fisheries risks to eels in order to obtain a more complete picture of their current status.
The independent review was recommended by the Parliamentary Commissioner for the Environment (the Commissioner) in a report on the status and management of longfin eels released in April 2013. The Commissioner called for “the establishment of a fully-independent peer review panel to assess the full range of information available on the status of the longfin eel population”.
“This is an important piece of work that will help to inform future eel research and monitoring,” says Dr Pamela Mace, Principal Advisor, Fisheries Science, Ministry for Primary Industries (MPI), who chaired the open sessions of the review.
The panel of experts noted the ubiquity of New Zealand eels, the relative richness of information sources, and the high quality of the analyses that have been undertaken by New Zealand scientists.
They agreed that there is a high probability that the longfin eel population has been substantially reduced relative to its pristine numbers given the biology of the species and the duration and extent of culling, habitat modification, damming and customary and commercial fishing. However, they also concluded that, in general, numbers have been relatively stable in recent years. In the South Island there are also examples of recent increases in standardised catch rates in some areas.
The panel considered, in detail, each of the current sources of information and analyses used for monitoring trends and assessing stock status, noting the limitations of each and, in most cases, making recommendations for improvement. They also suggested possible supplementary information that could be collected to further strengthen current monitoring. They recommended a comprehensive assessment that integrates conventional fisheries information with non-fisheries information, such as the impact of habitat degradation, pollution and other non-fisheries causes of mortality (e.g. hydro dams).
MPI’s Eel Science Working Group will meet later this month to discuss the review panel’s recommendations for modifying existing research programmes or implementing new ones. MPI and the Minister for Primary Industries, Nathan Guy, will consider management actions in light of the panel’s report in early 2014.
The panel members were:
Dr Alex Haro, a research ecologist with the S.O. Conte Anadromous Fish Research Laboratory (Ecosystems Mission Area, U.S. Geological Survey) at Turners Falls, Massachusetts.
Dr Willem Dekker, a fisheries scientist from the Swedish University of Agricultural Research. Dr Dekker has been involved in Dutch, Swedish and European studies on the status of the European eel stock.
Nokome Bentley, a New Zealand-based fisheries scientist and founder of Trophia Limited, a co-operative of independent fisheries scientists.
The panel’s report is available here:
2013 Independent review of theinformation available for monitoringtrends and assessing the status of New Zealand freshwater eels [PDF, 1.5 MB]