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Author: Cairbre Fanslow Publisher: ISBN: Category : Dungeness crab Languages : en Pages : 84
Book Description
Spatial and temporal genetic variation was assessed using mitochondrial DNA from adult and megalopae of Dungeness crabs, Cancer magister, from Fraser Delta in British Columbia, Washington, Oregon, and California. Megalopae were continuously sampled using light traps in one location, Coos Bay, Oregon, and compared with adults sampled across the species' range. While small-scale spatial and temporal variation were evident, there was no significant fit to the Isolation-by-Distance model when considering adult and larvae populations sampled over a coastal length of ~1700 km (Mantel r = 0.059, p = 0.289). Smaller bays showed higher genetic diversity than larger bays, contrary to typical expectations. MtDNA diversity measures (assessed by canonical correlation analysis) were correlated with bay size and depth, suggesting that hydrological patterns or fishing harvests in local areas (or a combination of both) influenced the observed genetic signature. The Dungeness crab ancestral population likely went through a historic population expansion associated with recent glacial relaxation, as evidenced by mismatch distributions and predominance of singleton haplotypes. In larval samples, we commonly observed numerous individuals of a haplotype, which suggests that families of larvae remain aggregated during dispersal. Sampled offspring revealed a low fraction of the adult gene pool (in accordance with the Hedgecock effect), yet high variability in recruitment over time. A realized long distance dispersal of larvae and the additive effects of recruitment from different sources over time may have prevented significant genetic differentiation within the C. magister range.
Author: Cairbre Fanslow Publisher: ISBN: Category : Dungeness crab Languages : en Pages : 84
Book Description
Spatial and temporal genetic variation was assessed using mitochondrial DNA from adult and megalopae of Dungeness crabs, Cancer magister, from Fraser Delta in British Columbia, Washington, Oregon, and California. Megalopae were continuously sampled using light traps in one location, Coos Bay, Oregon, and compared with adults sampled across the species' range. While small-scale spatial and temporal variation were evident, there was no significant fit to the Isolation-by-Distance model when considering adult and larvae populations sampled over a coastal length of ~1700 km (Mantel r = 0.059, p = 0.289). Smaller bays showed higher genetic diversity than larger bays, contrary to typical expectations. MtDNA diversity measures (assessed by canonical correlation analysis) were correlated with bay size and depth, suggesting that hydrological patterns or fishing harvests in local areas (or a combination of both) influenced the observed genetic signature. The Dungeness crab ancestral population likely went through a historic population expansion associated with recent glacial relaxation, as evidenced by mismatch distributions and predominance of singleton haplotypes. In larval samples, we commonly observed numerous individuals of a haplotype, which suggests that families of larvae remain aggregated during dispersal. Sampled offspring revealed a low fraction of the adult gene pool (in accordance with the Hedgecock effect), yet high variability in recruitment over time. A realized long distance dispersal of larvae and the additive effects of recruitment from different sources over time may have prevented significant genetic differentiation within the C. magister range.
Author: Tyler M. Jackson Publisher: ISBN: Category : Crab populations Languages : en Pages : 89
Book Description
Understanding connectivity among exploited populations is critical to their sustainable management and long-term viability. In the marine environment, estimates of connectivity often rely on the use of genetic markers, as dispersal primarily occurs during a planktonic larval phase which is difficult to track using direct methods. In this thesis, we investigated the population genetic structure of the most valuable commercially harvested species on the west coast of the United States, the Dungeness crab (Cancer magister). We utilized both population- and individual-based genetic analyses to establish baseline knowledge of genetic connectivity of Dungeness crab throughout ~1,200 km of the California Current System (CCS) in 2012, and tested for inter-annual variability in our estimates by sampling again in 2014. In 2012, we observed a pattern of isolation by distance despite there being little genetic population structure throughout our study range. In addition, several sites had significant evidence of kin aggregation, which was correlated with genetic differentiation as measured by pairwise FST. In 2014, pairwise FST estimates were noticeably lower, there was no spatial autocorrelation, and fewer sights had significant evidence of kin aggregation. We attributed these findings to increased migrant exchange during potential larval dispersal years, which was mediated by variation in physical oceanographic conditions (i.e. Pacific Decadal Oscillation phase, timing of the spring transition, amount of upwelling during the spring and summer). Dispersal trajectory, and thus gene flow, is likely influenced by variation in physical oceanographic conditions, thereby affecting genetic population structure. Estimates of effective population size (N[subscript E]) indicated that N[subscript E] was large in both 2012 and 2014, but we were unable to discern any change between years. Together, these findings suggest that Dungeness crab in the CCS may constitute a single evolutionary population, though geographically limited dispersal results in isolation by distance. We also evaluated genetic connectivity among Dungeness crab inhabiting a partially enclosed water body, Puget Sound, in comparison to those residing in the coastal ocean. With the exception of Hood Canal, we observed genetic homogeneity within both Puget Sound and coastal Washington. Genetic differentiation between Puget Sound and coastal Washington was variable among sites, therefore genetic connectivity is stronger within either area than between them. Overall, our results suggest that Dungeness crab exemplify characteristics of a ‘high gene flow’ species, despite evidence supporting geographically limited gene flow. Our findings did not indicate that altering the management strategy to reflect discrete genetic subunits or conversation needs (i.e. low genetic diversity) is necessary at this time. In addition, our findings highlight the need for future research to investigate demographic processes that influence gene flow (i.e. dispersal trajectory).
Author: Kenneth D. Waldron Publisher: ISBN: Category : Dungeness crab Languages : en Pages : 43
Book Description
Results of studies beginning in 1947 on the biology of the Dungeness crab (Cancer magister) in Oregon coastal waters are reported. A review is made of the history of the fishery with regard to trend of the catch by magnitude, area, and season; the development and conduct of the fishery itself; and the regulations governing the fishery. The first reported commercial crab landings in Oregon were 6,628 pounds in 1880. The fishery expanded slowly until 1933 after which the catch rose sharply to a peak of about 11 million pounds in 1943. Landings in recent years have fluctuated between 6 and 11 million pounds from a commercial fishery which is carried out along the major portion of the Oregon coast. During the period 1947-50, 6,249 tagged crabs were released in offshore and bay waters of Oregon and 34.6 percent of the tags were subsequently recovered. The average movement of 1,042 recoveries of crabs released in offshore waters, as measured by the distance from the tagging site, was 8.3 miles (range 0-133 miles) in 80 days. For crabs released within bays, 606 recoveries averaged a minimum distance traveled of 4.2 miles (range 0-81 miles). Fifty-seven percent of the recoveries of offshore releases and 84 percent of the recoveries of bay releases were made within 4 miles of the respective tagging sites. Over 90 percent of the recoveries of offshore releases were made within 6 months, although 3 crabs were out more than a year with 1 at liberty 878 days. Tagged crabs moved from offshore to bays, from bay to bay, and from bays to offshore. There was no significant difference in percentage recovery for crabs with or without missing appendages. Egg-bearing female crabs are present in offshore waters during the period October to March, inclusive. Larval crabs assumed to be C. magister were observed in offshore waters from April to July, inclusive. Considerable variation in early growth of post larval crabs was observed in laboratory experiments. The amount of growth of crabs between 6.4 and 146.0 mm., as observed by measuring them before and after molting, increases until a shoulder width of about 95 mm. is reached. The increase with each subsequent molt thereafter remains relatively constant. Macroplankton-eating fishes feed upon free swimming crab larvae. Adult crabs up to at least 114 mm. in shoulder width are preyed upon by voracious fish such as ling-cod (Ophiodon elongatus), the great marbeled sculpin (Scorpaenichthys armoratus), wolf eel (Anarrhichthys ocellatus), halibut (Hippoglossus stenolepis), and some of the rock fishes of the genus Sebastodes.
Author: Wongyu Park Publisher: ISBN: 9780549069089 Category : Dungeness crab Languages : en Pages : 165
Book Description
Mixing, loss, and distribution of larval Dungeness crabs were investigated inside and outside of Glacier Bay, southeastern Alaska, biweekly from late May to mid-September and monthly in Icy Strait from late May to late August in 2004. Larvae were collected from two different portions of the water column: above and below the thermocline and at four stations in Icy Strait. Larval loss was markedly high for ZI, ZIV, and ZV, and relatively low for ZII and ZIII. ZI occurred from late May to late July. Larval stages progressed seasonally from ZI to ZV and density decreased from ZI through ZV. The larval densities at the inner and outer bay stations and at the shallow and deep depths were similar.
Author: Cairbre Fanslow
Author: Cairbre Fanslow
Author: Tyler M. Jackson
Author: Valliammal Chockalingam
Author: Roderick C. Hobbs
Author: Corinne H. Lardy
Author: Richard Stanley Caldwell
Author: 
Author: Kenneth D. Waldron
Author: Wongyu Park
Author: Paul W. Wild