Study

Discards from the artisanal shrimp fishery in a tropical coastal lagoon of Mexico: spatio-temporal patterns and fishing gear effects

  • Published source details Burgos-León A., Pérez-Castañeda R. & Defeo O. (2009) Discards from the artisanal shrimp fishery in a tropical coastal lagoon of Mexico: spatio-temporal patterns and fishing gear effects. Fisheries Management and Ecology, 16, 130-138.

Actions

This study is summarised as evidence for the following.

Action Category

Use a larger codend mesh size on trawl nets

Action Link
Subtidal Benthic Invertebrate Conservation

Use a larger mesh size

Action Link
Marine Fish Conservation
  1. Use a larger codend mesh size on trawl nets

    A replicated, paired, controlled study (year unspecified) of three estuarine sites in the Celestun Lagoon, Gulf of Mexico, Mexico (Burgos-León et al. 2009) found that trawl nets fitted with a 2.5 cm mesh codend instead of a traditional 1.3 cm mesh caught fewer combined non-commercial unwanted invertebrate and fish species (discard) and lower biomass and abundance of discarded organisms. On average, nets with the larger mesh codend caught fewer discard species (3–12) than nets with the traditional codend (12–20). Biomass and abundance of discards were on average lower with the larger mesh codend (biomass: 2–10 g/245 m2; abundance: 0.7 individuals/245 m2) than with the traditional codend (biomass: 22–57; abundance: 37). Nets with the larger mesh codend also caught less biomass and abundance of commercially targeted shrimps (biomass: 3–15 g/245 m2; abundance: 1 individual/245 m2) than nets with the traditional codend (biomass: 15–39; abundance: 20). This however led to similar biomass ratios of commercially targeted to discard species for both mesh sizes (1:1). On three occasions at each of three sites, a vessel towed two identical bottom-nets simultaneously over 100 m during paired deployments, one fitted with the traditional codend, the other with the larger mesh codend. For each deployment, discarded organisms were identified and their combined weight and counts recorded. Weights of commercially targeted shrimps were also recorded.

    (Summarised by: Anaëlle Lemasson & Laura Pettit)

  2. Use a larger mesh size

    A replicated, paired, controlled study (year not stated) in an estuarine lagoon in the Gulf of Mexico, off Mexico (Burgos-León et al. 2009, same experimental set-up as Poot-Salazar et al. 2009) found that increasing the mesh size in a shrimp trawl codend reduced the overall unwanted catch (fish and invertebrates combined) compared to a conventional mesh size codend. Total discarded catch was lower with a 2.5 cm mesh size (0.9 individuals/245 m2) compared to a 1.3 cm mesh (3.2 individuals/245 m2). In addition, the 2.5 cm mesh size caught fewer unwanted smaller individuals than the 1.3 cm mesh size for six of the eight most important species. Target shrimp Farfantepenaeus spp. catch was also lower with the larger mesh size than the conventional mesh size (1.0 vs 2.7 individuals/245 m2). Three sites 3–5 km apart in the Celestun Lagoon (shallow, tidal) were sampled in three seasons (March-May, June-October and November-February, years unspecified). Two bottom nets (shrimp triangle) were fished simultaneously with different mesh-size codends: 2.5 cm mesh and a conventional 1.3 cm mesh used in the shrimp fishery. Three replicate samples were taken in each case. Unwanted fish and invertebrate catch and shrimps were sorted by species, counted and lengths measured.

    (Summarised by: Natasha Taylor)

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