Misspent youth: does catching immature fish affect fisheries sustainability?

Paraskevas Vasilakopoulos, Finbarr G. O'Neill, Tara Marshall

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)


The "spawn-at-least-once" principle suggests that sustainability is secured if fish become vulnerable to commercial gears only after they have spawned. However, some studies suggest that protecting immature fish is not essential to sustainability because extrinsic factors determine both recruitment and stock status. A meta-analysis was conducted to quantify the independent effects of exploitation pattern and exploitation rate on current stock status. The analysis used empirical data for 38 fish stocks of 13 species in the NE Atlantic. Two metrics of exploitation pattern were used and their sensitivity was compared. As expected, exploitation rate had a significant negative effect on current stock status. Exploitation patterns associated with high proportional fishing mortality of immature fish also had a significant negative effect on current stock status, providing empirical support for the "spawn-at-least-once" principle. When the fishing mortality of immature fish exceeds half that of mature fish, stock status falls below precautionary limits. Our results suggest that a sensitive metric of exploitation pattern could provide useful information about an aspect of exploitation that is currently overlooked by fisheries management regimes that focus primarily on exploitation rate.

Original languageEnglish
Pages (from-to)1525-1534
Number of pages10
JournalICES Journal of Marine Science
Issue number7
Publication statusPublished - Jul 2011


  • exploitation pattern
  • exploitation rate
  • fisheries management
  • ICES
  • meta-analysis
  • spawn-at-least-once
  • sustainability
  • cod Gadus-Morhua
  • stocks
  • recruitment
  • size
  • age
  • exploitation
  • management
  • variability
  • selectivity
  • experience


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