MESA: Pacific Ocean Perch Life History
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Rockfish eggs and larvae under magnification. |
There is much uncertainty about the life history of Pacific ocean perch (POP), although
generally more is known than for other rockfish species. The species appears to be
viviparous (the eggs develop internally and receive at least some nourishment from the
mother), with internal fertilization and the release of live young. Insemination occurs
in the fall, and sperm are retained within the female until fertilization takes place ~2
months later. The eggs hatch internally and parturition (release of larvae) occurs in
April-May.
Information on the early life history of POP is very sparse, especially for the first year of
life. Pacific ocean perch larvae are thought to be pelagic and drift with the current.
Oceanic conditions may sometimes cause advection to sub-optimal areas, resulting in high
recruitment variability. However, larval studies of rockfish have been hindered by difficulties
in species identification since many larval rockfish species share the same morphological
characteristics. Genetic techniques using allozymes and mitochondrial DNA are capable of
identifying larvae and juveniles to species, but are expensive and time-consuming.
Post-larval and early young-of-the-year Pacific ocean perch have been positively identified
in offshore surface waters of the GOA, which suggests this may be the preferred habitat of
this life stage. Transformation to a demersal existence may take place within the first year.
Small juveniles probably reside inshore in very rocky, high-relief areas, and by age 3 begin to
migrate to deeper offshore waters of the continental shelf. As they grow, they continue to migrate
deeper, eventually reaching the continental slope, where they reach adulthood.
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Adult Pacific ocean perch (left) and young-of-the-year (right). |
Contact:
Dana Hanselman
Auke Bay Laboratories
Alaska Fisheries Science Center, NOAA Fisheries
Ted Stevens Marine Research Institute
17109 Pt Lena Loop Rd
Juneau AK 99801
Dana.Hanselman@noaa.gov
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