Fish born in Marine Protected Areas recruit outside of network

STATEWIDE—Scientists with the Southwest Fisheries Science Center and UC Santa Cruz found a direct link between California’s Marine Protected Areas (MPAs) and its hypothesized benefit, according to a report published in the journal, Molecular Ecology.

Kelp rockfish born in MPAs near Monterey Peninsula were found to recruit in areas outside of the protected area, the team of ecologists and geneticists found.

The MPA-born kelp rockfish were found in non-MPA and State Conservation Areas, the UC Santa Cruz and Southwest Fisheries Science Center study found. Commercial and recreation harvests are generally allowed in these non-MPA and State Conservation Areas.

“Their study also found that fish born in MPAs dispersed to other nearby MPAs, demonstrating the network function of the MPA system in California,” a statement released by National Oceanic and Atmospheric Administration (NOAA) Fisheries. “While similar results have been reported from tropical reef MPAs, this is the first study to demonstrate such connectivity in a temperate marine ecosystem.”

Demonstrating a connection between protected and non-protected marine areas is one of the biggest challenges marine conservationists face, as it isn’t easy to track individual fish through marine environments.

“Tracking individual fish from birth through settlement into adult habitat is extremely difficult, due to both high mortality, and the enormous scale of marine habitat and fish populations,” NOAA Fisheries staff said in a statement about the study. “Further adding to the challenge is that rockfishes are part of a diverse group of closely related species that live in the same habitat and are extremely difficult to distinguish as juveniles.”

Researchers were able to overcome the practical challenge by implementing a technique called intergenerational genetic tagging, which uses gene data to identify pedigree relationships of tagged adult fish and their offspring.

Nearly 15,000 fish were sampled (non-lethally) over a four-year period. About 40 percent of the fish were identified as kelp rockfish, with eight of those sampled identified as parent-offspring pairs and 25 as pairs of full-siblings.

“Since kelp rockfish do not disperse after settlement into their adult kelp forest homes, a fact that was further confirmed by the team, the location of their settled offspring informs us about how far and to where juvenile kelp rockfish disperse,” NOAA Fisheries staff stated.

John Carlos Garza of Southwest Fisheries Science Center and Mark Carr and UC Santa Cruz led the research team.

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