Data Collection For Assessment Of Fished Cephalopod Stocks

(Research supported by the CEC, DGXIV Study Project 96/081)

OBJECTIVES

The primary aim of this project was to develop routine fishery and biological data collection for cephalopods, currently of significant fishery importance but not subject to quota management, in order to allow assessments to be made of the major European stocks, and to provide a model for standardized data collection which could be adopted by the relevant statutory bodies should cephalopod stocks be brought into the framework of the CFP. This builds on recent research concerning stocks on the squid Loligo in the northern Northeast Atlantic (UK and France), for which "depletion" methods of assessment have been shown to provide a promising approach.

The proposal encompasses three European countries: the UK, France and Spain and will involve collection of data on the four main categories of cephalopods landed from the NE Atlantic: long-finned (loliginid) squids, short-finned (ommastrephid) squids, cuttlefish and octopus. Accumulated knowledge on the life-cycle biology of these species leads us to believe that depletion methods of assessment can potentially be applied to stocks of all of these species.

The work proposed falls under five main headings, the first four of which specifically address gaps in current data collection in the three countries:

• monthly market sampling for biological parameters: depletion methods minimally require data on mean body weight and a recruitment index, and, where more than one species is landed together, these data are needed for each species and the proportion of each species in landings must be determined. Due to the variability in timing of recruitment and growth rates in cephalopod populations it is important to collect these data every year for which assessment is to be carried out.
• monthly market sampling to assess the quality of official fishery data: to identify and attempt to quantify sources of error (e.g. inadequate species identification). Where official statistics do not provide the necessary resolution of fishery information needed for assessment (particularly in Spain), there will be sampling at selected markets to collect representative data on landings, fishing effort and fishing areas. This will also allow the feasibility of real-time assessments to be evaluated.
• collecting information on discarding practices: currently, no official information is collected on the amount or size of cephalopods discarded, and patterns of discarding are unknown. The information collected will be used to improve estimates of fishing mortality.
• quantifying natural mortality: a limited program of fish stomach sampling (based on research cruise surveys) will be carried out, alongside a review of available data for other predatory species, to obtain improved estimates of natural mortality.
• data assembly and database maintenance: data collected during the project and acquired from other sources (e.g. landings data for other EU countries) will be added to an existing database of cephalopod life-cycle, fishery and ancillary data. The data will be used to carry out annual stock assessments.

Images from Vigo, July 1997

The following pictures were taken by Julio Martines Portela during and after the first Co-ordination Meeting for this project, held in Vigo in July 1997.

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