Estimating movement and abundance of Atka mackerel ( Pleurogrammus monopterygius) with tag–release–recapture data

• Published in: Fisheries Oceanography
• Main Authors: MCDERMOTT, SUSANNE F., FRITZ, L. W., HAIST, V.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2005
• Subjects: Atka; Petersen; Aleutian Island; Archipelago; Alaska; Aleutian Islands
• Online Access: http://dx.doi.org/10.1111/j.1365-2419.2005.00380.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-2419.2005.00380.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2419.2005.00380.x

Abstract A mark–recapture experiment was conducted in Seguam Pass, Alaska, to estimate local Atka mackerel ( Pleurogrammus monopterygius ) abundance and to evaluate the efficacy of trawl exclusion zones around Steller sea lion ( Eumetopias jubatus ) rookeries. Atka mackerel were found in dense aggregations near the Aleutian Islands where they are a major prey item of endangered Steller sea lions. In 1999, 1375 tagged fish were released and a biomass of 76 679 metric tonnes (t) was estimated outside a trawl exclusion zone using a simple Petersen model. In 2000, 8773 tagged fish were released and the estimated biomasses were 117 900 t inside and 82 057 t outside the trawl exclusion zones using an integrated tagging model. Movement into the open zone was small after 107 days (0.6%), whereas movement from the open area was potentially large but highly uncertain after 107 days (81%). Our model suggests that trawl exclusion zones in Seguam Pass are effective in separating a large biomass of potential prey for Steller sea lions from the immediate effects of local fisheries. Atka mackerel do not appear to move substantially outside their local aggregations (<70 km), and they show strong habitat preferences within their local home ranges. In one instance, fish released in an area of low Atka mackerel abundance returned to their capture location about 2 miles away. Thus individual Atka mackerel may have an affinity for particular areas within their home range, perhaps resulting from adaptations to local oceanic conditions along the Aleutian Island archipelago.