Distribution of Lobster Larvae (Homarus americanus) off Pictou, Nova Scotia

1968 ◽  
Vol 25 (2) ◽  
pp. 427-430 ◽  
Author(s):  
D. J. Scarratt
Keyword(s):  
Nova Scotia ◽  
Homarus Americanus

not available

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.

The Lobster (Homarus americanus) Fishery off Lower Argyle Southwestern Nova Scotia

1990 ◽  
Vol 47 (6) ◽  
pp. 1177-1184 ◽  
Author(s):  
Alan Campbell
Keyword(s):  
Nova Scotia ◽  
Fold Increase ◽  
Homarus Americanus ◽  
Weekly Basis ◽  
Index Numbers ◽  
Management Implications ◽  
Frequency Distributions ◽  
Fishing Season ◽  
Juvenile Abundance ◽  
Overall Mortality

Catch and effort data for the lobster (Homarus americanus) fishery of Lower Argyle, Nova Scotia, were obtained from sales slips on a weekly basis during 1978–87. Lobster size–frequency distributions were collected during at-sea sampling at the beginning and end of each fishing season. This fishery experienced a three-fold increase in landings (from 87.6 to 270 t) due to an increase in recruitment during the 10-yr study. The fishermen responded to the improved recruitment by increasing the total number of days fished per season by 41%. Overall mortality of recruited lobster (estimated from size–frequencies) rose from 55% in 1978 to 72–81% during 1985–87. During the 1987–88 fishing season, about 1 t lobster were removed per km2 of fishing grounds. Regression relationships between a prerecruit juvenile abundance index (numbers of lobster/trap haul) and the recruited yield one to two fishing seasons later were significantly correlated for 8–9 yr of data; equations predicted that lobster yields would remain high during the 1988–89 fishing season but decline in this area during 1989–90 fishing season. Management implications of forecasting recruitment yields 1–2 yr in advance and possible strategies to reduce major recruitment fluctuations in this fishery are discussed.

scholarly journals Risk factors associated with soft-shelled lobsters (Homarus americanus) in southwestern Nova Scotia, Canada

FACETS ◽  
2017 ◽  
Vol 2 (1) ◽  
pp. 15-33 ◽  
Author(s):  
Krishna K. Thakur ◽  
Crawford Revie ◽  
Henrik Stryhn ◽  
Shannon Scott Tibbetts ◽  
Jean Lavallée ◽  
...  
Keyword(s):  
Nova Scotia ◽  
Homarus Americanus ◽  
Eastern Canada ◽  
Related Factors ◽  
Mixed Effect ◽  
Shell Quality ◽  
Factors Associated ◽  
Regression Methods ◽  
Spatio Temporal ◽  
Ecosystem Changes

Soft-shelled lobsters pose economic challenges to the lobster industry due to low meat yields and survivability during holding and transportation. Our objectives were to describe spatio-temporal patterns of soft-shelled lobsters in southwestern Nova Scotia, and identify environmental and lobster-related factors associated with shell quality. We analyzed data obtained from a broad-scale, intensive monitoring project and remotely sensed water temperatures. Mixed-effect logistic regression and linear regression methods analyzed more than 130 000 samples collected between 2004 and 2014. The annual overall prevalence of soft-shelled lobsters ranged from 9% to 38% and varied significantly among fishing areas. Shell quality was influenced by sex and size, and in the 2 months before the fishing season, lower water temperatures (4–6 weeks prior to sampling) were associated with reduced prevalence of soft-shells. High annual variability of soft-shell prevalence, that water temperature alone could not explain, suggests that adjusting fishing seasons, arbitrarily, in two fishing areas will not improve the overall shell quality of landed lobsters. Further research is needed to evaluate the effects of long-term temperature and ecosystem changes on lobster health in eastern Canada.

Movements of Tagged American Lobsters, Homarus americanus, off Southwestern Nova Scotia

1985 ◽  
Vol 42 (2) ◽  
pp. 229-238 ◽  
Author(s):  
Alan Campbell ◽  
Aivars B. Stasko
Keyword(s):  
Nova Scotia ◽  
Continental Shelf ◽  
Carapace Length ◽  
Gulf Of Maine ◽  
Homarus Americanus ◽  
Long Distance ◽  
Mature Adults ◽  
Straight Line ◽  
Straight Line Distance ◽  
Long Distance Movement

A total of 4304 American lobsters (Homarus americanus) were tagged and released in inshore areas off southwestern Nova Scotia and on northwest Browns Bank during June–August 1975. Of the 424 lobsters recaptured within 5.4 yr of release, 385 had known recapture locations. For all release areas the average straight-line distance traveled by mature ([Formula: see text]carapace length) lobsters (15.6 km) was significantly greater than for immature (59–94 mm carapace length) lobsters (4.7 km). Most (69.3%) of the immature lobsters (N = 212) were recaptured less than 18.5 km (10 naut mi) from the release sites; for mature lobsters (N = 173) this percentage was 40.5%. Previous tagging studies off southwestern Nova Scotia revealed little evidence of long-distance movement; our study, however, shows that mature lobsters can move long distances. Many (19.7%) of the mature lobsters were recaptured more than 92.6 km (50 naut mi) from the release sites. The overall direction of travel was south, in both an east and west direction, with many lobsters moving greater than 50 km from coastal Nova Scotia and Browns Bank into the Gulf of Maine and to the slopes of the continental shelf. Thirteen lobsters moved from Browns Bank to inshore areas of southwestern Nova Scotia. The evidence of the long-distance interchange of a portion of the mature adults between southwestern Nova Scotia and the adjoining continental shelf suggests that lobsters in these areas could belong to a single stock.

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.

Effectiveness of lobster fisheries management in New Zealand and Nova Scotia from multi-species and ecosystem perspectives

2016 ◽  
Vol 74 (1) ◽  
pp. 146-157 ◽  
Author(s):  
Tyler D. Eddy ◽  
Julio N. Araújo ◽  
Alida Bundy ◽  
Elizabeth A. Fulton ◽  
Heike K. Lotze
Keyword(s):  
New Zealand ◽  
Nova Scotia ◽  
Fisheries Management ◽  
Single Species ◽  
Homarus Americanus ◽  
Maximum Sustainable Yield ◽  
Ecosystem Impacts ◽  
Ecosystem Effects ◽  
Trade Offs ◽  
Large Predators

In New Zealand and Nova Scotia, lobster (Jasus edwardsii and Homarus americanus, respectively) is the most valuable export fishery. Although stock assessments and indicators assist in evaluating lobster fisheries, ecosystem effects are largely unknown, hindering ecosystem-based fisheries management (EBFM). We employed ecosystem models for the Cook Strait, New Zealand and western Scotian Shelf, Nova Scotia, Canada, to evaluate trade-offs between catches and ecosystem impacts in lobster fisheries from single- and multi-species perspectives. We ran simulations to independently determine exploitation rates that produced maximum sustainable yield (MSY) for lobster, and for all fished groups. We then ran simulations using these MSY exploitation rates simultaneously, and simulations to maximize multi-species MSY (MMSY). Our results indicate that current lobster exploitation rates in both regions are greater than those producing MSY, and have significant ecosystem impacts. Simulating multi-species fisheries, in both systems the sum of single-species MSY for all fished groups was less than the sum of catches where exploitation rates were run simultaneously. Runs maximizing MMSY across the entire ecosystem increased exploitation rates on many fished groups, and produced even greater total catch—yet with much greater ecological costs—and in Nova Scotia, collapses of sharks, large predators, and lobster themselves. As fisheries management moves towards multi-species and ecosystem-based approaches, we suggest that MMSY targets should be treated similarly to MSY—not as a target, but a limit. Even then, careful evaluation is required before implementation to ensure that there are no undesirable economic or ecological consequences.

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

Large-scale Analysis of Atlantic Nova Scotia American Lobster (Homarus americanus) Landings with Respect to Habitat, Temperature, and Wind Conditions

1994 ◽  
Vol 51 (6) ◽  
pp. 1308-1321 ◽  
Author(s):  
Christiane Hudon
Keyword(s):  
Nova Scotia ◽  
Large Scale ◽  
Coastal Upwelling ◽  
Thermal Characteristics ◽  
Homarus Americanus ◽  
American Lobster ◽  
Cumulative Number ◽  
Northern Cape ◽  
Definition Of ◽  
Homogeneous Regions

American lobster (Homarus americanus) landings per unit of habitat, calculated for 25 statistical districts (SD) of Atlantic Nova Scotia (N.S.), were consistently higher in northern Cape Breton (SD 1–7) and southwestern N.S. (SD 32–34) than from the eastern (SD 15–18) and southern (SD 22–31) shores. Analyses suggest that changes in lobster populations of Atlantic N.S. take place over distances in the order of 100 km and over periods of about 5 yr and that lobster abundance is not limited by habitat availability. Five large homogeneous regions subject to similar historical landing trends could be identified on the basis of their thermal characteristics. Regions of lowest lobster landings (SD 8–31) are oriented in the axis of dominant southwest winds, which generate coastal upwelling, resulting in the lowest cumulative number of degree-days and a high year-to-year variability. Conversely, the high landings recorded in southwestern N.S. can be related to warm and stable temperature conditions, allowing lobsters to enhance yearly thermal gains via winter migrations into deep (> 100 m), warm Slope water. The definition of homogeneous regions characterized by common historical landing trends and thermal regime suggests that lobster abundance in Atlantic N.S. is ultimately controlled by large-scale oceanographic processes.

Dispersal of American Lobsters, Homarus americanus, Tagged Off Southern Nova Scotia

1989 ◽  
Vol 46 (11) ◽  
pp. 1842-1844 ◽  
Author(s):  
Alan Campbell
Keyword(s):  
Nova Scotia ◽  
Continental Shelf ◽  
Continental Slope ◽  
Gulf Of Maine ◽  
Homarus Americanus ◽  
Georges Bank ◽  
Scotian Shelf ◽  
Long Distance ◽  
German Bank ◽  
Long Distance Movement

Of the 5281 American lobsters (Homarus americanus) tagged and released off McNutt Island, South Nova Scotia, during 1983–87, 15.8% were captured within 3 yr of release. Although most immature (99%) and mature (86%) lobsters were caught < 18.5 km from release, mature lobsters moved a greater mean distance (25.8 km) than immature lobsters (3.6 km). Of the lobsters that moved > 30 km eight moved south to the continental slope near Browns Bank and 11 moved west of Cape Sable to the inshore areas of southwestern Nova Scotia, the midshore area of German Bank and offshore to Browns Bank and Georges Bank. This and other studies of tagged lobsters indicate that there is some movement of lobsters east and west of the Cape Sable area, the southern tip of Nova Scotia, suggesting some mixing between lobster stocks off eastern Nova Scotia and southwestern Nova Scotia. The long distance movement and mixing of mature lobsters suggests that attempts to use tagging information in locating biological boundaries between lobster stocks in the Gulf of Maine, adjoining Continental Shelf, Scotian Shelf and inshore areas of southwestern Nova Scotia and southern end of eastern Nova Scotia may be a difficult task.

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