|Updated on 31/05/2005|
Table of Contents:
The experience of the Spanish team, involved in a project on
the biology and fisheries of the red lobster in the Spanish Mediterranean
since 1997, as well as the financial support of the COPEMED project,
contributed to the standardization of the sampling methodology and a
joint comparative analysis of the results.
Two study areas are considered in this study:
Sampling program on commercial boats: a total of 130 hauls (87 from Spain, 43 from Tunisia) were sampled in 2001, during the spring and fall seasons. Data collected were:
Due to the impossibility of having precise individual weights on board commercial boats, length-weight relationships were calculated from research surveys conducted in the Columbretes Islands (for the Spanish data) and from Tunisian lobster pond (for the Tunisian data).
Laboratory sampling: In the laboratory, the following biological data/samples were collected: length, weight, maturity stage, gonad weight and color, gonad samples, diet information, moult stage, and samples for genetic analysis.
Logbook data covering the 2002 fishing season: 1149 hauls (468 from Spain, 681 from Tunisia) were registered. Data collected were:
Lobster landings from 1990 to 2002 were also collected from official Spanish and Tunisian fishery statistics.
Methods for data analysis
Statistical tests were used for a spatio-temporal analysis of the 2 fisheries. Non-lobster catches were used to estimate by-catch and discards.
Fleets Characteristics and Fishing
The fleets from Spain and Tunisia are composed of artisanal boats with technical characteristics closely related to the distance from their homeports to the fishing ground. While in Tunisia some 60 fishing units of medium to large size (14-16 mt) engage in lobster fishing during the season, in the Spanish Mediterranean a much larger number (> 250) of small artisanal vessels fish for lobster during the main part of the fishing season. The reason for this is that in Tunisia most of the productive fishing grounds are at distances from the coast over 60 nm while in Spain fishing for lobster takes place mostly within 30 nm from the coast. The landing strategies also differ. While in Tunisia most of the catches are landed in two harbours – Bizert and Tabarka – and are bought by “viveros” to be exported to European markets, in Spain lobster is landed in a myriad of small harbours where it is partially sold directly for fresh consumption locally.
Lobster fisheries are regulated in the two countries by minimum landing sizes (80 mm CL)
and closed seasons (September to February). However, in Tunisia there is the possibility of closing certain areas to fishing before the end of the season if there is evidence that the stock abundance is low. It is unclear whether this measure is applied.
Maërl substrates (free living cralline algae and associated zoobenthos) often associated with the brown algae Laminaria rodriguezii.
Size and Sex structure of lobster catch
Tunisian exploited populations have a greater proportion of large lobsters than populations exploited by the Spanish fleets. This could indicates higher levels of exploitation in the Spanish fishery than in the Tunisian fishery.
The depletion of both Spanish and Tunisian fisheries over the 1999-2000 period would reflect an intense exploitation.
Source: EDFAM project