Monitoring commercial eel fisheries
Project Title: Monitoring commercial eel fisheries
Project Code: EEL2004/02
Start Date: 1 October 2004
Completion Date: 30 September 2005
Vessel Use: Nil
Overall Objective:
- To monitor the size grades and species composition of commercially processed eels.
Specific Objectives:
- To monitor size of eels by recording quantities of eels by species (shortfin and longfin) in the different commercial size grades from defined areas.
Note:
This project will be subject to the review of project EEL2002/04 – Monitoring of commercial eel fisheries.
Rationale:
Commercial catches of eels have been sampled in both the North and South Islands over three consecutive seasons from 1995–96 to 1997–98 and in 1999–2000. The results showed that the size, and sex composition of longfins has been dramatically altered compared to the shortfin populations, with larger longfin female eels absent from main-stem river fisheries. Some longfin populations in more heavily fished areas are almost exclusively male. Analysis of catch-effort data from throughout New Zealand for the period 1990–91 to 2000–01 indicate a general decline in CPUE for longfin eels.
The Medium Term Research Plan for eel fisheries proposes periodic (3-5 years) catch sampling of the commercial eel fishery to monitor size frequency and species composition. A current project EEL2002/04 is designed to monitor the size and species composition of the commercial eel catch at processing premises. Of particular importance is to monitor the presence or absence of longfin females eels over the minimum size at migration. The previous catch sampling programmes have shown very few larger female longfin eels and this has raised concerns about spawning escapement. However eel processors and fishers have maintained that the catch sampling has not been completely representative of the size and species composition of eels processed from all areas. While the catch sampling programmes in the South Island have been effective in sampling commercial catches, and is being repeated in EEL2002/04, for logistical reasons sampling in the North Island has been less effective. Consequently the catch sampling programme to be carried out in EEL2002/04 only includes the South Island.
A new methodology is being trialed in EEL2002/04 for the North Island to monitor the size of eels by recording quantities of eels (separately for SFE and LFE) in the different commercial size grades in processing factories, and to relate these size grades to discrete areas (subsets of CELR Eel Statistical Areas - ESAs). Processors generally only grade into three size classes.
Female longfin eels above the minimum size at migration are only present in the largest size grade above 1kg. The landing of eels in this size grade can be apportioned to defined areas within catchments by data recorded by fishers and processors. Using this methodology, it should be possible to determine the proportions of different sized eels of both species in discrete areas from virtually all the landed catch throughout the country and avoid the problems associated with sampling sufficient landings to be representative of different areas. The methodology may allow the monitoring of the size grades of eels harvested from small defined areas on an annual basis, and to assess trends in the abundance of larger longfin eels in the commercial fishery.
Strategic Relevance
This project is consistent with the Fisheries Resources goal and Strategic Objectives in the Ministry of Fisheries Strategic Research Directions document.
Cost Recovery Information:
The percentage allocation for this project will be attributed to the following Fishstocks according to rule 9.2 of the Fisheries (Cost Recovery) Rules 2001:
All ANG stocks
All SFE and LFE stocks
The project is estimated to cost between $0 - $50,000.