Crossing Invisible Boundaries: the Effectiveness of the Langebaan Lagoon Marine Protected Area as a Harvest Refuge for a Migratory Fish Species in South Africa

• Published in: Conservation biology Vol. 23; no. 3; pp. 653 - 661
• Main Authors: KERWATH, SVEN E, THORSTAD, EVA B, NÆSJE, TOR F, COWLEY, PAUL D, ØKLAND, FINN, WILKE, CHRIS, ATTWOOD, COLIN G
• Format: Journal Article
• Language: English
• Published: Malden, USA Blackwell Publishing Inc 01-06-2009; Wiley-Blackwell; Blackwell Publishing Ltd
• Subjects: acoustic telemetry; AMP; Animal and plant ecology; Animal migration; Animal Migration - physiology; Animal, plant and microbial ecology; Animals; Applied ecology; Biological and medical sciences; Breeding seasons; Conservation; Conservation biology; Conservation of Natural Resources - methods; Conservation, protection and management of environment and wildlife; Demography; Ecosystem; Environmental monitoring; Female; Fish; fish migration; fish movement; Fisheries; Fisheries management; Fisheries science; Fishing lines; Fundamental and applied biological sciences. Psychology; lagoon; Lagoons; laguna; Male; Marine; Marine Biology; Marine fishes; marine reserve; migración de peces; Models, Theoretical; movimiento de peces; MPA; Ocean fisheries; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Perciformes - physiology; Reproduction - physiology; reserva marina; Rhabdosargus globiceps; Sea water ecosystems; Seasonal migration; Seasons; South Africa; Synecology; Telemetry; telemetría acústica; Transmitters; South Africa; Africa; PSW, South Africa, Western Cape, Langebaan Lagoon; Range finding; acoustic telemetry; Migration; marine reserve; Protected area; Refuge; lagoon; Marine environment; fish migration; Vertebrata; Migratory; fish movement; Pisces; Nature reserve; Environmental protection; MPA
• ISSN: 0888-8892; 1523-1739
• DOI: 10.1111/j.1523-1739.2008.01135.x

The application of no-take areas in fisheries remains controversial. Critics argue that many targeted species are too mobile to benefit from area protection and that no-take areas are only appropriate for resident species. The degree of protection does not depend on the size of the no-take area but rather on the time fish reside inside its boundaries during key life-history events (i.e., spawning) and during periods of peak fishing activity. We evaluated the potential of a small no-take marine protected area (MPA) inside a coastal embayment as a harvest refuge for a mobile, possibly migratory, long-lived fish species. We used acoustic telemetry to track movements of 30 transmitter-tagged white stumpnose (Rhabdosargus globiceps) across and on both sides of the boundary of a small (34 km²) no-take area over a full year. Being landlocked on 3 sides, the location of the MPA inside the lagoon made it practical to detect all boundary crossings and to calculate the time individual fish used the MPA. We detected frequent movements across the boundary, with strong seasonal and individual variations. There were significant differences in MPA use patterns between fish from different release areas. The time spent in the MPA by individual fish during summer (mean 50%; max 98%) was out of proportion with the size of that area (4% of total habitat). Summer coincided with peak recreational fishing activity and with the spawning season of this species. The small MPA provided a refuge for a part of the spawning stock of white stumpnose. Our findings suggest that if strategically placed, a small no-take area can be effective in protecting mobile species and that models of spillover from no-take areas should account for seasonal and individual variation in area use and the spatiotemporal distribution of fish and fishers.