Keep it simple: three indicators to deal with overfishing

Three simple fisheries indicators are presented: (i) percentage of mature fish in catch, with 100% as target; (ii) percent of specimens with optimum length in catch, with 100% as target; and (iii) percentage of ‘mega-spawners‘ in catch, with 0% as target, and 30–40% as representative of reasonable stock structure if no upper size limit exists. Application of these indicators to stocks of Gadus morhua, Sardinella aurita and Epinephelus aeneus demonstrate their usefulness. It is argued that such simple indicators have the potential to allow more stakeholders such as fishers, fish dealers, supermarket managers, consumers and politicians to participate in fisheries management and eventually hold and reverse the global pattern of convenience overfishing, which is defined here as deliberate overfishing sanctioned by official bodies who find it more convenient to risk eventual collapse of fish stocks than to risk social and political conflicts.

[1]  Johanna J. Heymans,et al.  Hundred‐year decline of North Atlantic predatory fishes , 2003 .

[2]  Y. Sadovy,et al.  The threat of fishing to highly fecund fishes , 2001 .

[3]  Rainer Froese,et al.  FishBase 2000: Concepts, designs and data sources , 2000 .

[4]  P. Solemdal Maternal effects — a link between the past and the future , 1997 .

[5]  B. Worm,et al.  Rapid worldwide depletion of predatory fish communities , 2003, Nature.

[6]  R. Beverton Patterns of reproductive strategy parameters in some marine teleost fishes , 1992 .

[7]  D. Pauly,et al.  Fishing down marine food webs , 1998, Science.

[8]  R. Froese,et al.  Empirical relationships to estimate asymptotic length, length at first maturity and length at maximum yield per recruit in fishes, with a simple method to evaluate length frequency data , 2000 .

[9]  G. I. Murphy Vital Statistics of the Pacific Sardine (Sardinops Caerulea) and the Population Consequences. , 1967, Ecology.

[10]  Ransom A. Myers,et al.  Maximum reproductive rate of fish at low population sizes , 1999 .

[11]  E. Trippel Egg Size and Viability and Seasonal Offspring Production of Young Atlantic Cod , 1998 .

[12]  R. Beverton Longevity in fish: some ecological and evolutionary considerations. , 1987, Basic life sciences.

[13]  Alan R. Longhurst,et al.  Murphy's law revisited: longevity as a factor in recruitment to fish populations , 2002 .

[14]  D. Pauly On Malthusian overfishing , 1990 .

[15]  G. Mertz,et al.  THE LIMITS OF EXPLOITATION: A PRECAUTIONARY APPROACH , 1998 .

[16]  J. Craig Aging in fish , 1985 .