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The 1994 stock assessment for the red rock lobster (Jasus edwardsii) fishery

By: Breen, P.A.
Contributor(s): Kendrick, T.H. (NIWA. Wellington) | NIWA Wellington (N.Z.).
Material type: materialTypeLabelBookSeries: New Zealand fisheries assessment research document ; 95/23.Publisher: Wellington : NIWA, 1995Description: 50 p.Subject(s): RED ROCK LOBSTERS | NEW ZEALAND | FISHERY RESOURCES | STOCK ASSESSMENT | FISHING EFFORT | CATCH COMPOSITION | BIOMASS | FISHING MORTALITYOnline resources: Click here to access online In: New Zealand fisheries assessment research documentSummary: This document updates commercial catch and effort data from the red rock lobster fishery and discusses and updates estimates of other catch components. Analysis of standardised CPUE for each of three substocks is briefly described and illustrated. Further analysis for the southern (NSS) substock, where CPUE showed a "significant" decrease as defined by the decision rule, is described. This was made with a generalised observation-error time series surplus production model. The inclusion of auxiliary information on exploitation rate and the inclusion of production residuals is also described. Results of this work show that the NSS substock is at a small percentage of virgin biomass and less than half the optimum biomass. However, estimated current surplus production is greater than likely removals, so the stock has a good chance of increasing in the near future. Size frequency data were used to estimate current total mortality rates for several areas where catch sampling is conducted. Morphometric relations between carapace length and tail width are presented. Size at maturity data were analysed from tail width sizes, and relations are presented. Growth estimates were revisited and slightly revised formulations are presented. Yield- and egg-per-recruit analyses were conducted for four areas, and a series of reference fishing mortality rates calculated. These are compared with the estimated current fishing mortality rates: in all four areas, current fishing intensity exceeds #F#/sub max/; in the two southern areas it also exceeds #F#/sub 25%/. (auths.)
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Item type Current location Call number Copy number Status Date due Barcode
JOURNAL JOURNAL WELLINGTON
JOURNALS
NO. 95/23 1 Available J09948

38 refs; 8 tables; 9 figs

Not to be cited without permission of the author(s)

This document updates commercial catch and effort data from the red rock lobster fishery and discusses and updates estimates of other catch components. Analysis of standardised CPUE for each of three substocks is briefly described and illustrated. Further analysis for the southern (NSS) substock, where CPUE showed a "significant" decrease as defined by the decision rule, is described. This was made with a generalised observation-error time series surplus production model. The inclusion of auxiliary information on exploitation rate and the inclusion of production residuals is also described. Results of this work show that the NSS substock is at a small percentage of virgin biomass and less than half the optimum biomass. However, estimated current surplus production is greater than likely removals, so the stock has a good chance of increasing in the near future. Size frequency data were used to estimate current total mortality rates for several areas where catch sampling is conducted. Morphometric relations between carapace length and tail width are presented. Size at maturity data were analysed from tail width sizes, and relations are presented. Growth estimates were revisited and slightly revised formulations are presented. Yield- and egg-per-recruit analyses were conducted for four areas, and a series of reference fishing mortality rates calculated. These are compared with the estimated current fishing mortality rates: in all four areas, current fishing intensity exceeds #F#/sub max/; in the two southern areas it also exceeds #F#/sub 25%/. (auths.)

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