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Three decades of longlining in Bimini, Bahamas, reveals long‐term trends in lemon shark Negaprion brevirostris (Carcharhinidae) catch per unit effort
Author(s) -
Kessel S. T.,
Hansell A. C.,
Gruber S. H.,
Guttridge T. L.,
Hussey N. E.,
Perkins R. G.
Publication year - 2016
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/jfb.12987
Subject(s) - catch per unit effort , biology , iucn red list , fishery , trough (economics) , population , geography , abundance (ecology) , ecology , demography , sociology , economics , macroeconomics
In Bimini, Bahamas, the consistent employment of longlines, beginning in 1982, provided a rare opportunity to explore population trends for large resident sharks. This study assessed three shallow water longline survey periods at this location; 1982–1989, 1992–2002 and 2003–2014, with the aim of determining trends in annual catch per unit effort ( CPUE ) for an IUCN listed near‐threatened species, the lemon shark Negaprion brevirostris . A general additive model ( GAM ) was used to analyse the non‐linear annual CPUE values over the entire 32‐year research period. The GAM displayed high variability of annual CPUE , with a peak value of 0·026 N. brevirostris per hook day (hooks day −1 ) in 2000. The temporal pattern of CPUE indicated an abundance trend with a complete cycle, from trough to trough, occurring over a period of approximately 18 years. The 1982–1989 survey period saw the highest proportion of mature individuals (19·8%) and the smallest average pre‐caudal length ( L PC ; 124·8 cm). The 1992–2002 survey period had the highest average annual CPUE (0·018 hooks day −1 ), while the 2003–2014 research period saw largest average L PC size (134·8 cm) and the lowest average CPUE values (0·009 hooks day −1 ) of the entire research period. The long‐term trend identified in this study provides a baseline for future assessment.