Spatial and Temporal Overlap of the American Lobster (Homarus americanus) and Sea Scallop (Placopecten magellanicus) as Related to the impact of Inshore Scallop Dragging

1992 ◽  
Vol 49 (7) ◽  
pp. 1486-1492 ◽  
Author(s):  
D. L. Roddick ◽  
R. J. Miller
Keyword(s):  
Nova Scotia ◽  
Homarus Americanus ◽  
Fishing Effort ◽  
The Other ◽  
American Lobster ◽  
Placopecten Magellanicus ◽  
Time And Space ◽  
Sea Scallop ◽  
The Impact ◽  
Temporal Overlap

Assessment of the damage of one fishery by another requires knowledge of the overlap, in time and space, of the damaging fishing effort and the abundance of the damaged species, as well as a measure of the rate of damage. This approach was used to measure the impact of inshore scallop dragging on lobsters in Nova Scotia. Areas of reported co-occurrence of lobster and scallop grounds were surveyed by divers to determine the extent of overlap. Only 2 of 52 sites surveyed had lobsters on scallop grounds that could be dragged. Divers surveyed one site six times during 1987 and 1988 and found lobsters most abundant during August and September. Only 2% of the lobsters in the path of scallop drags were either captured or injured. The estimated value of lobsters destroyed by dragging for scallops during periods of peak lobster abundance was minor: $757 at one site and $176 at the other. Restricting dragging to periods of low lobster abundance significantly reduces this cost.

Temperature and Lobster, Homarus americanus, Yield Relationships

1991 ◽  
Vol 48 (11) ◽  
pp. 2073-2082 ◽  
Author(s):  
A. Campbell ◽  
D. J. Noakes ◽  
R. W. Elner
Keyword(s):  
Nova Scotia ◽  
New Brunswick ◽  
East Coast ◽  
Homarus Americanus ◽  
Fishing Effort ◽  
Sea Surface ◽  
Time Series Models ◽  
American Lobster ◽  
Sea Temperature ◽  
Survival And Growth

Commercial landings of American lobster (Homarus americanus) have increased dramatically in many areas along the east coast of Canada since the late 1970's. Average annual sea surface temperatures (SST) were analysed to test if lobster landings were related to changes in the marine environment. Time series models were fitted to lobster landings and SST data from Maine (USA), Halifax County (Nova Scotia), and Charlotte County (New Brunswick). Including temperature in the models improved forecasting ability for lobster catches for Maine and Halifax but not Charlotte. In Maine, lobster landings in year t were related to SST in year t. In Halifax, however, landings were related to SST in the previous 4 yr but not by SST of the current year. Lower fishing effort levels for Halifax compared with Maine probably extended the yield from strong year-classes through a number of years. We surmise that an increase in sea temperature near Halifax during the early 1980's increased the survival and growth rates of lobster juveniles. This provided a strong pulse of recruits to the fishery throughout coastal Nova Scotia during the mid- to late 1980's. Similar increases in temperature and landings were not observed for Maine and Charlotte.

Predation of Sea Scallops, Placopecten magellanicus, by the Rock Crab, Cancer irroratus, and the American Lobster, Homarus americanus

1979 ◽  
Vol 36 (5) ◽  
pp. 537-543 ◽  
Author(s):  
Robert W. Elner ◽  
Glen S. Jamieson
Keyword(s):  
Prey Size ◽  
Homarus Americanus ◽  
American Lobster ◽  
Prey Selectivity ◽  
Placopecten Magellanicus ◽  
Cancer Irroratus ◽  
Sea Scallop ◽  
Open Sea ◽  
Rock Crab ◽  
Sea Scallops

Various predation techniques used by rock crabs, Cancer irroratus, and American lobsters, Homarus americanus, to open sea scallop, Placopecten magellanicus, prey are reported. Adult rock crabs and lobsters successfully fed on sea scallops up to 72 and 76 mm in height, respectively. Juvenile lobsters were capable of preying on scallops whose height exceeded their own carapace length. Daily predation rates on a range of scallop sizes by various sizes of predator were obtained. Given a choice, both rock crabs and lobsters showed distinct and constant preferences for certain size scallops. This preferred prey size increased with predator size. These laboratory studies demonstrated that both rock crabs and lobsters are potential scallop predators. Key words: sea scallops, crabs, lobsters, predation techniques, prey selectivity

scholarly journals Quantifying relative fishing impact on fish populations based on spatio-temporal overlap of fishing effort and stock density

2013 ◽  
Vol 70 (3) ◽  
pp. 618-627 ◽  
Author(s):  
Morten Vinther ◽  
Margit Eero
Keyword(s):  
Fishing Effort ◽  
Fish Populations ◽  
Fishing Mortality ◽  
Fishing Impact ◽  
Management Measures ◽  
Stock Assessments ◽  
Spatio Temporal ◽  
Substantial Decline ◽  
The Impact ◽  
Temporal Overlap

Abstract Vinther, M., and Eero, M. 2013. Quantifying relative fishing impact on fish populations based on spatio-temporal overlap of fishing effort and stock density. – ICES Journal of Marine Science, 70: 618–627. Evaluations of the effects of management measures on fish populations are usually based on the analyses of population dynamics and estimates of fishing mortality from stock assessments. However, this approach may not be applicable in all cases, in particular for data-limited stocks, which may suffer from uncertain catch information and consequently lack reliable estimates of fishing mortality. In this study we develop an approach to obtain proxies for changes in fishing mortality based on effort information and predicted stock distribution. Cod in the Kattegat is used as an example. We use GAM analyses to predict local cod densities and combine this with spatio-temporal data of fishing effort based on VMS (Vessel Monitoring System). To quantify local fishing impact on the stock, retention probability of the gears is taken into account. The results indicate a substantial decline in the impact of the Danish demersal trawl fleet on cod in the Kattegat in recent years, due to a combination of closed areas, introduction of selective gears and changes in overall effort.

scholarly journals LARGE EPIBENTHIC INVERTEBRATES IN THE BRAS D’OR LAKES

2002 ◽  
Vol 42 (1) ◽  
Author(s):  
M. John Tremblay
Keyword(s):  
Egg Production ◽  
Carcinus Maenas ◽  
Homarus Americanus ◽  
Strongylocentrotus Droebachiensis ◽  
Green Crab ◽  
American Lobster ◽  
Placopecten Magellanicus ◽  
Cancer Irroratus ◽  
Trawl Surveys ◽  
Epibenthic Invertebrates

The distribution of large epibenthic invertebrates (lobster and crabs, bivalve molluscs and echinoderms) in the Bras d’Or Lakes is reviewed, and possible limiting factors are identified. The review is based on published and unpublished studies, including recent trawl surveys directed at fish, and trapping studies directed at American lobster Homarus americanus and green crab Carcinus maenas. The reduced salinities within the Lakes probably limit the distribution of several species (rock crab Cancer irroratus, sea scallop Placopecten magellanicus and possibly American lobster), particularly during the more sensitive larval period. Lobsters and eastern oysters Crassostrea virginica serve to illustrate the multiple factors limiting epibenthic invertebrate distribution within the Bras d’Or Lakes. Lobsters are less abundant within the Bras d’Or Lakes than on the outer coast of Cape Breton Island. Possible reasons are the reduced salinity and limited cobble bottom substrate in the Bras d’Or Lakes, coupled with low food availability and low egg production. Low egg production may be the result of overfishing of lobsters in the past. The life history and physiology of the eastern oyster appears to be well suited to the areas of the Lakes with warm summer temperatures. The oyster populations in the Bras d’Or Lakes are limited by natural predators (e.g. starfish and green crab), competitors (e.g. blue mussel Mytilus edulis and M. trossulus), and overfishing. The green crab, a new arrival to the Bras d’Or Lakes, will likely have negative effects on bivalves such as oysters, but the overall effect of green crab on the Bras d’Or Lakes food web is difficult to predict. Recent trawl surveys indicate both sea urchins Strongylocentrotus droebachiensis and starfish are present in considerable abundance, but little is known about their ecological roles in the Bras d’Or Lakes.La distribution des grands invertébrés épibenthique (les homards et les crabes, les mollusques bivalves et les échinodermes) dans les lacs du Bras d’Or est examinée et les coefficients possiblement limitatifs sont identifies. La revue est basée sur des études publiées et non-publiées englobant les plus récentesétudes sur la pêche au chalut dirigées vers les poissons et les études sur la pêche aux casiers dirigées vers les homards américains Homarus americanus et les crabes verts Carcinus maenas. Salinités réduites dans les lacs du Bras d’Or limitent probablement la distribution de quelques espèces crabes roches Cancer irroratus, pétoncle géant Placopecten magellanicus et possiblement le homard américain, en particulier, pendent l’époque sensible du larvaire. Les homards et les huîtres de l’Est Crossostrea virginica montrent plusieurs facteurs coefficients limitatifs de la distribution des invertébrés épibenthique dan les lacs du Bras d’Or. Les homards sont moins abondants ici que sur la côte extérieure de L’Ille du Cap Breton. Des explications possibles sont la réduction de l’eau saline du pavé rond limite dans le substratum de lacs, ainsi que la pauvre disponibilité de mangé et la production basse des oeufs. Cette dernière est peut-être le résultat d’un trop grand prise de homards au passè. L’histoire et la physiologie des huîtres semblent être bien adaptés aux lieux des lacs de Bras d’Or, qui ont des temperatures chaudes dan l’été. La population des huîtres dans les lacs est limitée par des proies natures ( ie étoiles de mer et les crabes verts) compétiteurs ( ie. Moules bleus Mytilus edulis et M. trossulus) et une trop grande prise de poissons. Le crabe vert, une arrivée nouvelle dans les lacs du Bras d’Or va sans doute avoir des impacts négatifs sur les bivalues comme les huîtres, mais leurs impacts en general sur la chaîne nutritive est difficile à prédire. Les études les plus recents sur la pêche au chalut montrent qu’il y a ungrand nombre d’oursins de mer Strongylocentrotus droebachiensis et des étoiles de mer, mais on ne connait pas quel est leur rôle écologique dans les lacs du Bras d’Or.

scholarly journals Evaluating benthic impact of the Gulf of Maine lobster fishery using the swept area seabed impact (SASI) model

2021 ◽  
Author(s):  
Andrew G Goode ◽  
Jonathan H Grabowski ◽  
Damian C. Brady
Keyword(s):  
Gulf Of Maine ◽  
Fish Habitat ◽  
Fishing Effort ◽  
American Lobster ◽  
Fishing Gear ◽  
Marine Habitats ◽  
Small Footprint ◽  
Lobster Fishery ◽  
The Impact ◽  
Swept Area

The Magnuson-Stevens Fishery Conservation and Management Act mandates U.S. fisheries minimize adverse effects of fishing on essential fish habitat (EFH). The Gulf of Maine (GoM) American lobster fishery is the most valuable U.S. fishery, and can deploy more than three million traps annually. To date, the impact of this fishery on benthic EFH has not been addressed quantitatively. To evaluate the impact of the GoM lobster fishery on EFH, lobster fishing effort was incorporated into a model linking habitat susceptibility and recovery to area impacted by fishing gear; the Swept Area Seabed Impact model. Impact to EFH was localized along the coast and highest along mid-coast Maine. Upwards of 13% of the benthos is in the process of recovery, but between 99.92 – 99.96% of initially affected habitat fully recovers. These estimates suggest that lobster fishing negligibly contributes to accumulation of EFH damage in the GoM due to the expansive area fished and the small footprint of each trap. Identifying areas of persistent impact is crucial in developing effective fisheries management for critical marine habitats.

scholarly journals Associations of lobsters (Homarus americanus) off southwestern Nova Scotia with bottom type from images and geophysical maps

2009 ◽  
Vol 66 (9) ◽  
pp. 2060-2067 ◽  
Author(s):  
M. John Tremblay ◽  
Stephen J. Smith ◽  
Brian J. Todd ◽  
Pierre M. Clement ◽  
David L. McKeown
Keyword(s):  
Nova Scotia ◽  
Homarus Americanus ◽  
Marine Science ◽  
Underwater Imaging ◽  
Placopecten Magellanicus ◽  
Bottom Type ◽  
Sediment Size ◽  
Significant Relationships ◽  
Line Transects ◽  
Animal Presence

Abstract Tremblay, M. J., Smith, S. J., Todd, B. J., Clement, P. M., and McKeown, D. L. 2009. Associations of lobsters (Homarus americanus) off southwestern Nova Scotia with bottom type from images and geophysical maps. – ICES Journal of Marine Science, 66: 2060–2067. Images from an underwater towed vehicle (Towcam) were used to estimate densities and to evaluate bottom-type associations of lobsters (Homarus americanus), crabs (Cancer spp.), and scallops (Placopecten magellanicus). Images were obtained in October 2006 along 14 line-transects off southwestern Nova Scotia in an area with productive lobster and scallop fisheries. Lobsters were observed in 4% of the 2044 images, crabs in 7%, and scallops in 40%. On sand, gravel, and cobble seabed, lobsters were readily observable. On rougher substrata with boulders, some lobsters were still evident either in the open or partially hidden in shelters. Estimated densities of lobsters from the images on some transects were 0.04 m−2, approximately half of the estimates of lobster density for adjacent inshore areas from scuba, but 34 times higher than estimates from scallop drags in the same area. Models of animal presence by bottom type were evaluated with categories that were (i) geophysically based (map of bottom type from geophysical characteristics) and (ii) image-based (sediment size from images). Significant relationships were evident with both types of seabed categorization, suggesting that it would be beneficial to stratify surveys using geophysical categories. Depth was also significant in determining presence/absence of lobsters and crabs. There is potential to develop indicators of lobster abundance using underwater imaging, and stratification by bottom type should be incorporated into surveys.

Historical Review of Lobster Life History Terminology and Proposed Modifications To Current Schemes

Crustaceana ◽  
1996 ◽  
Vol 69 (5) ◽  
pp. 594-609 ◽  
Author(s):  
Peter Lawton ◽  
Kari L. Lavalli
Keyword(s):  
Life History ◽  
Size Range ◽  
Historical Review ◽  
Homarus Americanus ◽  
Behavioral Changes ◽  
American Lobster ◽  
Behavioral Attributes ◽  
Developmental Phases ◽  
The Impact ◽  
Current Terminology

AbstractTerms for the life history and developmental phases of the American lobster, Homarus americanus, vary substantially and have been frequently revised (Cobb et al., 1983; Hudon, 1987; Barshaw & Bryant-Rich, 1988; Wahle & Steneck, 1991; Cobb & Wahle, 1994). Their evolution shows several trends: (1) acknowledgement of pronounced morphological, physiological, and behavioral changes accompanying a metamorphic molt into the fourth pelagic stage; (2) recognition of behavioral changes (facilitated by decreasing mortality risk) leading to increased vagility over the size range ~ 5 to 40 mm carapace length (CL), and (3) consideration of the impact of reproductive maturation on lobster movement and social interaction. Before further modifying current terminological schemes (Wahle & Steneck, 1991; Cobb & Wahle, 1994), a historical perspective is provided and problems with existing schemes are presented. Our proposed scheme, which better integrates ecological ontogeny with developmental, biological, and individual behavioral attributes, partitions the life history into seven phases (exclusive of the attached egg and prelarval stages): pelagic larval, postlarval, shelter-restricted juvenile, emergent juvenile, vagile juvenile, adolescent, and adult. It should also provide a template from which to standardize life history schemes for spiny lobsters where there are similar problems with current terminology.

Relationship Between Destructive Grazing by the Sea Urchin, Strongylocentrotus droebachiensis, and the Abundance of American Lobster, Homarus americanus, on the Atlantic Coast of Nova Scotia

1981 ◽  
Vol 38 (11) ◽  
pp. 1339-1349 ◽  
Author(s):  
W. G. Wharton ◽  
K. H. Mann
Keyword(s):  
Population Structure ◽  
Nova Scotia ◽  
Sea Urchins ◽  
Atlantic Coast ◽  
Homarus Americanus ◽  
Strongylocentrotus Droebachiensis ◽  
American Lobster ◽  
History Of ◽  
Kelp Bed ◽  
The Relationship

Relationships between percentage cover of macroalgae, population structure of sea urchins (Strongylocentrotus droebachiensis), and the history of the lobster fishery were examined at nine sites distributed along the Atlantic coast of Nova Scotia from Guysborough County in the northeast to Pubnico in the southwest. At Pubnico there was dense algal cover and a small number of urchins living in crevices, and at Cape Sable there was an area of transition, but at all other sites there were urchin-dominated barren grounds. When the population structure of the urchins was compared with that previously observed in St. Margaret's Bay before, during, and after destruction of beds of kelp (Laminaria spp. and Agarum) by overgrazing, it was concluded that kelp bed destruction occurred on the coast north of Halifax prior to 1970, and on the coast south of Halifax after 1970. From the records of American lobster (Homarus americanus) catches it was concluded that a critical decline in catches at each site occurred a few years after kelp bed destruction. Information from various sources is synthesized into a coherent theory of the relationship between lobsters, other predators, sea urchins, and kelp.Key words: lobsters, Homarus americanus; sea urchins, Strongylocentrotus droebachiensis; destructive grazing, kelp, Laminaria, Agarum

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