Study

A conservation trade-off? Interspecific differences in seahorse responses to experimental changes in fishing effort

  • Published source details Curtis J.M.R., Ribeiro J., Erzini K. & Vincent A.C.J. (2007) A conservation trade-off? Interspecific differences in seahorse responses to experimental changes in fishing effort. Aquatic Conservation: Marine and Freshwater Ecosystems, 17, 468-484

Actions

This study is summarised as evidence for the following.

Action Category

Cease or prohibit all towed (mobile) fishing gear

Action Link
Subtidal Benthic Invertebrate Conservation

Cease or prohibit mobile fishing gears that catch bottom (demersal) species and are dragged across the seafloor

Action Link
Marine Fish Conservation
  1. Cease or prohibit all towed (mobile) fishing gear

    A replicated, controlled, before-and-after study in 2000–2002 of 14 sites within seagrass beds in the Ria Formosa lagoon, southern Portugal (Curtis et al. 2007) found that ceasing towed gear fishing led to increases in the cover of mobile invertebrates, but not non-moving (sessile) invertebrates, after 10 months. Cover of mobile invertebrates increased after towed-gear fishing stopped (3.9%) compared to before it stopped (1.1%), but not cover of sessile invertebrates (before: 2.8%; after: 2.7%). No changes were reported at sites where experimental fishing continued and at sites never fished (data not provided; no statistical comparisons were made with sites where fishing stopped). The use of towed demersal gears for commercial and recreational purposes is prohibited in the Ria Formosa. Experimental towed gear fishing started in October 2000 at 12 sites (monthly 10 m tow of a beach seine, 9 mm mesh) and stopped at nine of them in September 2001. Cover of sessile and mobile invertebrates (>2.5 cm) was surveyed at all sites and two nearby sites that were never fished during underwater visual surveys (180 m2/site) before fishing stopped (August–September 2001) and 10 months after (June–July 2002).

    (Summarised by: Anaëlle Lemasson)

  2. Cease or prohibit mobile fishing gears that catch bottom (demersal) species and are dragged across the seafloor

    A replicated, controlled, before-and-after study in 2000–2002 of 17 sites in a lagoon in the North Atlantic Ocean, Portugal (Curtis et al. 2007) found that densities of long-snouted seahorse Hippocampus guttulatus, but not short-snouted seahorse Hippocampus hippocampus, increased when bottom seine fishing (a mobile gear) was ceased, compared to sites where seining fishing effort remained constant. At sites where experimental seining was ceased after one year, the average density of long-snouted seahorses increased to 0.07 from 0.03/m2 and was higher than fished and unfished sites (0.03/m2) in both years. However, densities of short-snouted seahorses decreased (0.02 to <0.01/m2) and were lower than fished and unfished sites (ceased: <0.01/m2, fished: 0.02/m2). Experimental fishing was done in the Ria Formosa coastal lagoon in southern Portugal using a beach seine in October 2000–October 2002. A total of 12 sites were seined each month during the first year, but no seining was done at these sites during the second year. Three other sites were fished monthly in both years and two sites were unfished (not seined in either year). All sites were surveyed once each year from June–September by scuba divers using standard underwater visual census techniques along three belt transects 30 m long and 2 m wide (180 m2/sampling site). Sea horse species were counted, and trunk lengths recorded. Full survey specifications are detailed in the original paper.

    (Summarised by: Chris Barrett)

Output references

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