TITLE

Reconciling overfishing and climate change with stock dynamics of Atlantic cod (Gadus morhua) over 500 years

AUTHOR(S)
Rose, G. A.
PUB. DATE
September 2004
SOURCE
Canadian Journal of Fisheries & Aquatic Sciences;Sep2004, Vol. 61 Issue 9, p1553
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
To examine overfishing and climate effects on depleted cod (Gadus morhua) stocks, a surplus production model based on reconstructions of cod catch in Newfoundland was used to describe biomass dynamics from 1505 to 2004. Productivity parameters r (population growth rate) and K (carrying capacity) were assigned by fitting model to survey biomass. Assumptions of fishery-only influences inferring constant, random, or depensatory parameters fared poorly (did not mimic history), as did climate influences indexed by tree ring growth. However, a model using both climate and depensation fared well, mimicking much documented history of Newfoundland cod, including declines during the Little Ice Age (mid- to late 19th century) and the stock collapses of the late 20th century, with a good fit to recent scientific surveys (r2 = 0.80). This model suggests temporal differentiation between fishing and climate effects, including (i) declines during the Little Ice Age (1800–1880) caused by lower productivity, (ii) collapses in the 1960s caused by overfishing, (iii) collapses in the late 1980s caused by both, and (iv) rebuilding now hindered by depensatory effects of low numbers.
ACCESSION #
15230728

Tags: FISHING;  CLIMATIC changes;  ATLANTIC cod;  GADUS;  BIOMASS

 

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