Spatial evidence for information exchange and competition in the Gulf of St. Lawrence snow crab (Chionoecetes opilio) fishery

2006 ◽  
Vol 63 (2) ◽  
pp. 254-267 ◽  
Author(s):  
Darren M Gillis ◽  
Elmer Wade ◽  
Douglas P Swain
Keyword(s):  
Information Exchange ◽  
Personal Information ◽  
Spatial Scales ◽  
Ideal Free Distribution ◽  
Public Information ◽  
Fishing Effort ◽  
Spatial And Temporal Variation ◽  
Snow Crab ◽  
Chionoecetes Opilio ◽  
Crab Abundance

Throughout the 1990s, the Gulf of St. Lawrence snow crab (Chionoecetes opilio) harvest provided an example of effective co-management in a developing fishery. The Department of Fisheries and Oceans Canada (DFO) and the snow crab fleet (the fleet) shared information that coordinated management and exploitation throughout the season. A preseason survey by DFO provided resource distributions prior to the fishery's opening. In-season monitoring allowed managers to track spatial and temporal variation in crab availability. This level of detail allowed the application of the ideal free distribution as a management and conservation tool. However, proper justification for its application requires the demonstration of information exchange and competitive effects. The spatial distribution of effort suggests that both of these are present. Fishing effort was influenced by public information and potential information exchange within the fleet. Reduced aggregation at smaller spatial scales suggests competition in trap placement. Thus, increasing fleet size may have a disproportionately small impact on fishing mortality because of limitations in information exchange and the lack of personal information in the new vessels. However, the nonlinear relationship between crab abundance and catch rates suggests that managers should avoid policies that increase fishing effort during times of low crab abundance.

Spatial distribution of catch and effort in a fishery for snow crab (Chionoecetes opilio): tests of predictions of the ideal free distribution

2003 ◽  
Vol 60 (8) ◽  
pp. 897-909 ◽  
Author(s):  
Douglas P Swain ◽  
Elmer J Wade
Keyword(s):  
Spatial Distribution ◽  
Resource Distribution ◽  
Ideal Free Distribution ◽  
Snow Crab ◽  
Catch Per Unit Effort ◽  
Chionoecetes Opilio ◽  
Free Distribution ◽  
Crab Abundance ◽  
Ideal Free ◽  
The Ideal

The ideal free distribution (IFD), a hypothesis from behavioural ecology, predicts that fishery effort should map resource distribution better than catch-per-unit-effort (CPUE) when interference competition occurs in the fishery. We tested this prediction using data from the fishery and annual research survey for snow crab (Chionoecetes opilio) in the southern Gulf of St. Lawrence. Effort was positively correlated with the local abundance of crabs in all years. Correlations between CPUE and local crab abundance were also positive in some years, but negative in others. In the latter cases, CPUE and effort were also negatively correlated, suggesting intense competition in the fishery. In most years, CPUE tended to be equalized among areas compared with the distributions of effort and local crab abundance, as predicted by the IFD. In most years, differences in spatial distribution were more significant between CPUE and crab abundance than between effort and crab abundance. Although effort was the more reliable indicator of resource distribution, even it provided a distorted view of this distribution, as predicted given expected violations of IFD assumptions. For example, effort tended to be higher than expected on fishing grounds near home ports and lower than expected on distant grounds.

Life history schedule and periodic recruitment of female snow crab (Chionoecetes opilio) in the eastern Bering Sea

2012 ◽  
Vol 69 (3) ◽  
pp. 532-550 ◽  
Author(s):  
Billy Ernst ◽  
David A. Armstrong ◽  
Julián Burgos ◽  
J.M. (Lobo) Orensanz
Keyword(s):  
Bering Sea ◽  
Mature Female ◽  
Snow Crab ◽  
Age At Maturity ◽  
Eastern Canada ◽  
Chionoecetes Opilio ◽  
Frequency Distributions ◽  
Eastern Bering Sea ◽  
Crab Abundance ◽  
Mean Size

Snow crab ( Chionoecetes opilio ) populations have fluctuated cyclically in eastern Canada and the eastern Bering Sea, where recruitment to the mature female pool has occurred over a period of three decades (1978–2007) in pulses with a mean period of 7 years. It has been hypothesized that this was the result of a parent–offspring relation between sequentially linked strong cohorts of mature primiparous females, which requires that periodicity matches the time lapsed between egg extrusion by the maternal broodstock and the offspring reaching maturity. We show that female age at maturity (post-settlement) varies between 4.5 and 7.5 years, with most females maturing at 5.5–6.5 years (7–8 years after egg extrusion). Pulses of female recruitment to the mature population do not show a latitudinal trend, consistent with uniformity in age-at-maturity. Results of tracking crab abundance and size–frequency distributions in cod stomach and trawl samples between successive pulses of the cycle are consistent with the hypothesis of serial linkage among pulses. Periodicity is reflected in trends of clutch fullness and average shell condition and in the negative correlation between the strength of primiparous female cohorts and the mean size of their members.

scholarly journals Bt corn growing information system in Cagayan Province, Philippines: An analysis for enhanced extension delivery service

2021 ◽  
Vol 8 (3) ◽  
Author(s):  
Marissa Hernando-Valdez ◽  
Cecilia H Delos Trinos
Keyword(s):  
Information System ◽  
Information Exchange ◽  
Information Sources ◽  
Personal Information ◽  
Public Information ◽  
Bt Corn ◽  
Economic Information ◽  
Exchange Of Information ◽  
Total Information ◽  
Information Score

The adoption of Bacillus thuringiensis (Bt) corn gene has increased production and agricultural information exchange plays a vital role towards sustained production growth. The study examined the information system by assessing the usefulness of information, frequency of consultations and strength of information exchange in Bt corn production in Cagayan Province, Philippines. Using descriptive correlation design, it was revealed that both technical and economic information from all sources were rated useful. Technical information on seed variety, land preparation, weather forecast, soil management and fertilizer application are frequently utilized while on the economic information only current market prices was frequently used. Frequency of Consultation with personal information sources gained the highest mean value of 5.02 signifying a two to three times exchange of information. Public information sources obtained an average mean of 2.80 which means four or five times contact in a year. This reveals the gap between the corn growers and public information sources. For the mass media sources, both radio (4.56) and television (4.72) are frequently used at two to three times a month. Personal information sources showed strong (224.25 IS) exchange of information between and among the Bt corn growers which comprise their communication network. Total information scores from public and mass media information sources revealed weak exchange of information. The total information score is significantly correlated with membership to organization, years of membership, nature of membership, land ownership and position in the farm. Total information score from friends, radio and newspaper showed significant relationship with income. Thus, information exchange with friends, listening to radio and reading newspaper had a significant influence on the increase of corn growers’ income.

scholarly journals Size-at-maturity shift in a male-only fishery: factors affecting molt-type outcomes in Newfoundland and Labrador snow crab (Chionoecetes opilio)

2020 ◽  
Author(s):  
Darrell R J Mullowney ◽  
Krista D Baker
Keyword(s):  
Population Density ◽  
Newfoundland And Labrador ◽  
Cold Water ◽  
Large Male ◽  
Snow Crab ◽  
Size At Maturity ◽  
Chionoecetes Opilio ◽  
Factors Affecting ◽  
Male Density ◽  
Process Factors

Abstract A sex-asymmetric downward shift in size-at-terminal-molt has recently occurred in males in some portions of the Newfoundland and Labrador (NL) snow crab stock range, a first known occurrence for such processes in snow crab (Chionoecetes opilio) stocks. This study examines plausible factors promoting the shift in size-at-terminal-molt [synonymous with size-at-maturity (SaM)] including individual size, temperature, population density, and sex ratio. Analyses highlight expanse of cold water and large male density as being significant predictors of molt-type outcomes. A confluence of cold conditions and low density of large males promoted the SaM shift. In turn, the low male density was associated with recently elevated fishery exploitation rates under quota-controlled management. It remains unknown the extent to which the reduction in terminal size reflects a phenotypic vs. genotypic process. Factors affecting skip-molting in male snow crab are investigated, and we find that skip-molting occurs most frequently under extreme cold and high population density conditions. Potential complications arising from altered growth dynamics are discussed. Overall, the results advance knowledge on intraspecific competition processes within snow crab populations and inform fisheries management systems that male-only harvest strategies do not provide full protection from biological harm to aquatic resources through fishing.

scholarly journals Panmixia in Alaskan populations of the snow crab Chionoecetes opilio (Malacostraca: Decapoda) in the Bering, Chukchi, and Beaufort Seas

2014 ◽  
Vol 34 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Gregory T. Albrecht ◽  
Kris J. Hundertmark ◽  
Alexandra E. Valentin ◽  
Sarah M. Hardy
Keyword(s):  
Snow Crab ◽  
Chionoecetes Opilio

SHELL STRENGTH AND CARAPACE SIZE IN NON-ADULT AND ADULT MALE SNOW CRAB (CHIONOECETES OPILIO)

2000 ◽  
Vol 20 (2) ◽  
pp. 399-406 ◽  
Author(s):  
J-D. Dutil ◽  
C. Rollet ◽  
R. Bouchard ◽  
W. T. Claxton
Keyword(s):  
Adult Male ◽  
Snow Crab ◽  
Chionoecetes Opilio

Fishing the line: catch and effort distribution around the seasonal haddock (Melanogrammus aeglefinus) spawning closure on the Scotian Shelf

2013 ◽  
Vol 70 (7) ◽  
pp. 973-981 ◽  
Author(s):  
A. van der Lee ◽  
D.M. Gillis ◽  
P. Comeau ◽  
P. Hurley
Keyword(s):  
Ideal Free Distribution ◽  
Fishing Effort ◽  
Additive Models ◽  
Catch Rate ◽  
Melanogrammus Aeglefinus ◽  
Boundary Line ◽  
The West ◽  
Fishing The Line ◽  
The Impact ◽  
Effort Distribution

Permanent and seasonal area closures are a common regulatory strategy in multispecies fisheries; however, few studies have closely examined seasonal closures. We examined the impact of the Browns Bank spawning closure on the spatial distribution of fishing effort and how the fleet utilized a “fishing the line” strategy. Generalized estimating equations were used to examine changes in effort distribution when the closure was and was not in effect. Effort displaced from the bank concentrated primarily within two areas up to 30 km from the closure boundary, one along the east boundary line and one along the west. Trends in catch rate (as value) with distance from the line were further examined using generalized additive models during the closed period, with results differing between regions. In the east, areas of greater catch rate could be identified and typically corresponded to areas of greater effort, while in the west region, no trends in catch rates were often observed, potentially indicating vessel distributions that correspond to the ideal free distribution. Implementation of a seasonal area closure on Browns Bank resulted in concentrations of vessels near the closure boundary, suggestive of a fishing the line strategy, with specific catch rate trends depending on vessel spatial distributions and target species.

Tissue specificity and ontogeny of lactate dehydrogenase in snow crab, Chionoecetes opilio (Brachyura, Majidae)

1994 ◽  
Vol 108 (3) ◽  
pp. 385-395 ◽  
Author(s):  
Annie Angers ◽  
François Pothier ◽  
Jean-Marie Sévigny ◽  
Bernard Sainte-Marie
Keyword(s):  
Lactate Dehydrogenase ◽  
Tissue Specificity ◽  
Snow Crab ◽  
Chionoecetes Opilio
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