| Genetic identification of progeny of MPA-resident copper rockfish (S. caurinus) – self-recruitment or emigration? Lorenz
Hauser, The University of Washington, Seattle |
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The extent of larval retention and natal homing in demersal fish is a topic central to the design and the efficacy of Marine Protected Areas (MPAs). Unfortunately, little is known about effective larval dispersal in many marine species. The duration of the pelagic phase in many species suggests extensive dispersal, and population genetic studies indicate large-scale exchange of migrants, though there is also recent evidence for surprisingly limited realized dispersal. Here, we use genetic markers (microsatellites) to identify the offspring of resident adult brown rockfish (Sebastes auriculatus) among incoming settling juveniles on an isolated artificial reef at Point Heyer in Puget Sound, thus directly estimating rates of self-recruitment on the reef. Due to low marker variability, unambiguous identification of these offspring from empirical data was not possible. However, one of the juveniles genetically matching an adult was confirmed as its offspring by otolith marking. Furthermore, comparison between observed and simulated data pointed towards an upper limit for self-recruitment. Combining all information, our data suggested a self recruitment rate between 2 and 10%. Although more data are needed, this suggests that for small protected areas, some rockfish progeny will recruit back to their "natal" reef, while others will disperse to occupy other habitats. The implication is that under the right circumstances, protected areas can serve as a nursery ground for the recruitment of fish in non-protected areas. |
| Publications resulting from this research |
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Hauser L., L. Newton, L. LeClair, and R. Buckley. 2007. Genetic identification of progeny of reef-resident brown rockfish (Sebastes auriculatus). In Biology, Assessment, and Management of Pacific Rockfishes, Proceedings of the Lowell Wakefield Fisheries Symposium, Anchorage Sept 2005, AK-SG-07-01: 99-119. pdf Multiple paternity in brown rockfish (Sebastes auriculatus). In preparation. |
| Presentations resulting from this research |
| Society Annual Meeting, Anchorage Hauser L, Newton L, LeClair L, Buckley R (March 2005) Finding Nemo in Puget Sound: parental identification of brown rockfish juveniles. Puget Sound Georgia Basin Research Conference. Everett M (Sept 2004) Paternity tests on juvenile Brown rockfish (Sebastes auriculatus) via microsatellite analysis. Final capstone project presentation. Hauser L (April 2004) The Marine Molecular Biotechnology Laboratory (MMBL) Presentation to Craig Hogan, Vice Provost of Research, UW. |
| Management outcomes |
| One of the main assertions of MPAs is that protecting a spawning biomass of marine fishes will enhance progeny output, and that the patterns of larval dispersal from the MPAs will contribute to local and/or regional stocks. However, the dispersal of marine fish larvae is poorly documented and this basic assumption remains unproven. Although clearly only a ‘snapshot’ in time, Hauser's results suggest that, at least on Point Heyer, recruitment of the 2004 year class occurred primarily from outside the resident population. If this is true, it implies that the Point Heyer population of spawning adults could be an important source of larvae for other reefs. Our simulations clearly demonstrated the feasibility of the approach of identifying offspring of resident adults, which will be a powerful tool for estimating rockfish dispersal into and out of MPAs. |