Premium
ASSESSING THE EFFECTIVENESS OF RELEASING COD LARVAE FOR STOCK IMPROVEMENT WITH MONITORING DATA
Author(s) -
Chan Kung-Sik,
Stenseth Nils Christian,
Kittilsen Marte O.,
Gjøsæter Jakob,
Lekve Kyrre,
Smith Tim,
Tveite Stein,
Danielssen Didrik
Publication year - 2003
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/1051-0761(2003)013[0003:ateorc]2.0.co;2
Subject(s) - fjord , hatchery , fishery , population , abundance (ecology) , biology , ichthyoplankton , fisheries management , demersal zone , cod fisheries , ecology , oceanography , pelagic zone , fishing , fish <actinopterygii> , demography , sociology , geology
Beginning in the 1880s, management of marine fisheries by hatching and releasing yolk‐sac‐stage larvae was advocated in both the United States and Norway. Major cod hatchery programs were popular in both countries until the mid‐20th century, despite lack of evidence that cod abundance increases with release of hatchery‐reared fish larvae; the potential value for such management procedures was repeatedly advocated throughout the 20th century. In Norway, a beach‐seine monitoring program was begun in the early 1900s to collect data on fall abundance of 6‐mo‐old demersal fish in 21 fjords along the Norwegian Skagerrak coast and is still going on. We used these data in conjunction with hatchery data on numbers of yolk‐sac larval cod released each spring in several fjords to test for an effect of the releases on the abundance of fjord cod populations. Using both a permutation test and a statistically derived time‐series model for the cod's population dynamics, we found a slight, but statistically significant, dependence of 6‐mo‐old cod abundance on the number of yolk‐sac larvae released in four of the 16 fjords (for which we had adequate release and beach‐seine data needed for carrying out the testing). However, using the time‐series model, we did not find evidence of long‐term increases in the abundance of mature cod in any of the fjords. We discuss our findings on the basis of the literature on marine fish population enhancement programs worldwide.