Fish, sex and growth

Haddock are a demersal (=bottom-living) fish found throughout the coastal regions of the North Atlantic, from northeast U.S. to Norway. Related to Atlantic cod, Haddock are commercially fished throughout their range, with most caught using bottom trawling. After decades of overfishing, good management and strong recruitment in recent years has promoted high abundances in some regions. Decades of fishing pressure, however, has changed their life history characteristics.

Haddock (image from

Haddock (image from

Before 1970, Haddock would typically take 4 years to reach 50 cm in length, but during the 1980’s and 90’s most Haddock reached this size within 3 years. Today, it’s again about 4 years. These changes likely result from density-dependent growth rates. When Haddock are uncommon, due to overfishing, there is little competition for food so the few remaining Haddock grow fast. At high abundances, competition for food is intense and growth is comparatively slow.

Age at sexual maturity has also changed, with most female Haddock reproducing now at 3 years instead of 4 years. For most fish species, however, fecundity or the number of eggs produced is related to body size/age, with older and larger females producing more eggs. Although maturing quicker has increased the spawning stock biomass (i.e. more sexually mature Haddock), reproductive success and the number of juvenile fish entering the population may actually be lower in years to come.

BOI has recently ranked Haddock and found that it has a “yellow” score, so a better alternative than red-listed Atlantic Cod but not as sustainable as green-listed Walleye Pollock and Pacific Cod.

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