Juneau Nature

Natural & cultural history of Juneau & Southeast Alaska

Juneau Nature - Natural & cultural history of Juneau & Southeast Alaska

Groundfish

Older than us

Black rockfish (Sebastes melanops), nicknamed ‘brown bombers.’ Unlike the more sedentary reef-dwelling rockfish, this species feeds in surface and midwater schools.

Black rockfish (Sebastes melanops), nicknamed ‘brown bombers.’ Unlike the more sedentary reef-dwelling rockfish, this species feeds in surface and midwater schools.

In years leading up to the 3rd edition of The Nature of Southeast Alaska, I grew increasingly concerned about the way industry and managers treat extremely long-lived, basically irreplaceable species. I contacted Kristen Munk, recently retired from a career aging groundfish for the Alaska Dept of Fish and Game. This led to a 3-page sidebar (p 211) called Harvesting longevity. Here’s the section on Groundfish:

“While salmon are famous for rapid growth and early mortality, most Pacific groundfish—bottom-oriented marine species—generally demonstrate the opposite reproductive strategy. As on land, many of our high-latitude sea creatures grow more slowly and live longer than their counterparts from lower latitudes.

Most fish are aged by examining their sagittal otoliths, a pair of small bones in the inner ear. . . Annuli are counted, as with trees or sectioned animal teeth. Also as in trees, slower growth in later life creates tighter, less-distinct rings. Otolith age-reading is an art as much as a science.

Published studies indicate that Pacific groundfish species of deep, cold water tend to live longer than shallow warm-water species. Quillback rockfish are an important commercial species, sold at fish markets. With a reported longevity of 90 years, quillback can be older than the people eating them! Unfortunately, fish market workers can rarely identify the rockfish species at their counters for the conscientious consumer.”