Management measures for self propagated future recovery of crawfish, Palinurus elephas, in Welsh waters.

Research output: Book/ReportCommissioned report

Abstract

Populations of the crawfish, Palinurus elephas, in Welsh waters have declined significantly since the 1960s and 1970s when changes in fishing practice took place. This large benthic crustacean is a key species in reef features within existing marine Special Areas of Conservation (SACs) and also within the wider context of the Welsh marine ecosystem. Recovery of crawfish populations is considered important in gaining Good Environmental Status (GES) for marine ecosystems under the Marine Framework Strategy Directive (MSFD). This report assesses the potential for both existing and potential management measures to aid in the self-propagated recovery of crawfish populations in Welsh waters and makes some recommendations on future data collection requirements.

One of the main difficulties in carrying out an assessment of management measures in facilitating crawfish recovery is a lack of data on both the biology and fishery of this species, which means that analytical stock assessments are not possible. The potential for recovery is therefore assessed based on existing knowledge of the biology of this species from throughout its geographical distribution, and from studies carried out on other spiny lobsters. Fisheries data, in the form of landings per unit effort (LPUE), has been collected for crawfish fisheries in south Wales since the 1980s under a shellfish permit scheme put in place by the South Wales Sea Fisheries Committee (SWSFC). This dataset has been identified as a benchmark to represent recovery towards an interim recovering target heading towards a population with the relevant characteristics to represent GES.

Existing management measures include minimum landing sizes (MLS), nature conservation designations, and a non-commercial catch limit. While the catch limits and MLS are specific to crawfish they have not elicited any increase in LPUE since they were introduced. The nature conservation designations currently in place do not have any mandatory management measures specific to crawfish, although there is a voluntary closed area to netting within the Skomer Marine Nature Reserve (NMR) and a voluntary no-take of crawfish by recreational divers. The assessment concluded that none of the management measures currently in place are likely to contribute to the recovery of crawfish in Welsh waters.

Of the potential management measures assessed, those which controlled fishing activity were deemed to have the most potential to aid crawfish recovery, as opposed to new nature conservation designations. Both appropriately selected area closures and a prohibition on the landing of crawfish have potential to both reduce fishing mortality and increase the reproductive output of the population. The introduction of appropriate minimum and maximum landing sizes concurrently, and prohibitions on the landing of berried crawfish, both have the potential to increase the reproductive output of the population. Some of the fisheries management measures assessed were deemed to be more suitable for application within a recovering population. These included gear restrictions, prohibitions of individual fishing methods, catch limits, and seasonal closures. Highly Protected Marine Conservation Zones (HPMCZ) in Wales and Marine Conservation Zones (MCZ) in England were also assessed, however, their relatively small size and focus on supporting ecosystem diversity and function may limit their potential to benefit the recovery of crawfish.

Further research is required in order to determine which of the management measures would be most effective in facilitating the recovery of crawfish populations in Welsh waters. At present it is not clear if increases in the reproductive output of the population would directly result in increased recruitment to the population. The connectivity of populations within Welsh waters is also important in determining at what level management measures may need to be introduced. Due to the lack of information surrounding recruitment to Welsh crawfish populations, management measures which both reduce removals from the population and increase the potential reproductive output are likely to be most effective in facilitating recovery. Further information is also required to make a determination of whether or not Welsh populations would benefit from management measures implemented at the EU or regional seas level. The legislative framework for implementing fisheries management measures is an important consideration on the effectiveness of management measures and should be taken into consideration during the decision making process.
Original languageEnglish
Place of PublicationBangor
PublisherCountryside Council for Wales (CCW)
Commissioning bodyCountryside Council for Wales (CCW)
Number of pages63
Volume989
Publication statusPublished - 2012

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Keywords

  • crawfish
  • palinurus elephas
  • fisheries conservation
  • Wales

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