Reproductive Potential of Three American Lobster (Homarus americanus) Stocks in the Canadian Maritimes

1983 ◽  
Vol 40 (11) ◽  
pp. 1958-1967 ◽  
Author(s):  
A. Campbell ◽  
D. G. Robinson
Keyword(s):  
Nova Scotia ◽  
Egg Production ◽  
Reproductive Potential ◽  
Homarus Americanus ◽  
Curvilinear Relationship ◽  
Bay Of Fundy ◽  
American Lobster ◽  
Female Size ◽  
New Information ◽  
Stock Recruitment

New information on female size at maturity, fecundity, and relative egg production per recruit is presented for American lobsters (Homarus americanus) from three areas in the Canadian Maritimes. Based on pleopod examination, sizes at 50% maturity for females were estimated at 108.1 mm carapace length (CL) from the Fundy area (Bay of Fundy and southwestern Nova Scotia), at 92.5 mm CL from eastern Nova Scotia, and at 78.5 mm CL from Northumberland Strait. There was a curvilinear relationship between the number of eggs per female and CL. An egg-per-recruit model predicted that in all three areas the second and third molt groups beyond the legal minimum recruit size contribute the most to egg production under current exploitation rates. Lobsters in Northumberland Strait and eastern Nova Scotia produce up to 30–50% of their eggs at sizes smaller than those at which females from the Bay of Fundy start to produce eggs. Although the stock–recruitment relationships for H. americanus are unknown, the egg-per-recruit assessment suggests that all three areas would benefit in egg production increases by increasing minimum legal recruit size by one molt increment.

Female American lobster (Homarus americanus) size-at-maturity declined in Canada during the 20th and early 21st centuries

2018 ◽  
Vol 75 (6) ◽  
pp. 908-924 ◽  
Author(s):  
Marthe Larsen Haarr ◽  
Bernard Sainte-Marie ◽  
Michel Comeau ◽  
M. John Tremblay ◽  
Rémy Rochette
Keyword(s):  
Egg Production ◽  
Homarus Americanus ◽  
American Lobster ◽  
Past Century ◽  
Female Size ◽  
Strongly Correlated ◽  
Size At Maturity ◽  
The Past ◽  
Evolutionary Response ◽  
Intense Exploitation

Changes in the environment and fishing have been shown to affect life-history characteristics, such as size or age of maturation, in a number of finfish and invertebrates. The American lobster (Homarus americanus) supports Canada’s most valuable fishery and exploitation rates are high. Female size-at-maturity (SM) is an important parameter in management of this species, as it is used in establishing minimum legal size regulations. In this study, we show with historical and recent data that SM of female American lobsters has declined across most of Canada, in some areas by as much as 30%, over the past 10–80 years. The spatial patterns of these declines are inconsistent with patterns of rising ocean temperature and lobster abundance (density). They are, however, strongly correlated to the strength of size-based fishery selection, and egg-per-recruit modeling indicates a gain in lifetime egg production associated with observed SM declines under a range of realistic harvesting scenarios. These findings suggest that the marked decrease we document in SM of female American lobsters in Canada over the past century represents an evolutionary response to intense exploitation.

Declining fecundity and factors affecting embryo quality in the American lobster (Homarus americanus) from the Bay of Fundy

2015 ◽  
Vol 72 (3) ◽  
pp. 352-363 ◽  
Author(s):  
Heather N. Koopman ◽  
Andrew J. Westgate ◽  
Zachary A. Siders
Keyword(s):  
Embryo Quality ◽  
Gulf Of Maine ◽  
Energy Content ◽  
Homarus Americanus ◽  
Striking Difference ◽  
Bay Of Fundy ◽  
American Lobster ◽  
Female Size ◽  
Factors Affecting ◽  
Old Females

Recent perturbations in ecosystem and environmental dynamics in the habitat of the American lobster have led to increases in abundance, with unprecedented high landings in some regions. Despite the commercial value of this species, surprisingly little is known about maternal and environmental influences on its reproductive output. We measured fecundity and embryo quality in 1370 ovigerous lobsters from the Bay of Fundy, Canada, during 2008–2013. Female size was generally positively correlated with fecundity (P < 0.001), although some of the very large (and presumably old) females brooded significantly fewer eggs than expected. Egg energy content and lipid content and composition exhibited significant annual differences, indicating environmentally based variation. The most striking difference was a 31% decline in fecundity from 2008 to 2013 (8%–10% per year). We hypothesize that recent warming trends could be responsible for reduced fecundity. Decreased fecundity may be a cause for concern for future recruitment in this population, which has been shown to be an important source of larvae for the Gulf of Maine metapopulation.

Spatial and temporal variation in size at maturity for female American lobster in Nova Scotia

2013 ◽  
Vol 70 (8) ◽  
pp. 1240-1251 ◽  
Author(s):  
Fiona L. Watson ◽  
Robert J. Miller ◽  
Samuel Alan Stewart
Keyword(s):  
Nova Scotia ◽  
New England ◽  
Egg Production ◽  
Development Stage ◽  
Fold Change ◽  
Minimum Size ◽  
Spatial And Temporal Variation ◽  
Bay Of Fundy ◽  
American Lobster ◽  
Size At Maturity

Using the development stage of cement glands to predict spawning, maturity ogives were constructed for six fishing ports in eastern Nova Scotia. The size at which 50% of females attained maturity (L50) and the ogive slopes were compared between locations and years. Among ports within years, 21 of 25 L50 pairs were significantly different, while only 5 of 24 slope pairs were different. These results fill a geographic gap and indicate that most of the areas should not be grouped when calculating egg production. Comparing among years within ports, most significant differences were again for L50 rather than slopes. In two ports, the change in the ogive among years gave a 2- or 2.4-fold change in eggs per recruit and a 2.9- or 5-fold change in the percentage of females that reach maturity by the legal minimum size. On a larger scale, L50 was intermediate in Newfoundland, consistently low throughout the southern Gulf of St. Lawrence, abruptly increased on the outer coast of Nova Scotia into the Bay of Fundy, and again intermediate inshore and offshore New England.

Relative Egg Production and Abundance of Berried Lobsters, Homarus americanus, in the Bay of Fundy and off Southwestern Nova Scotia

1986 ◽  
Vol 43 (11) ◽  
pp. 2190-2196 ◽  
Author(s):  
A. Campbell ◽  
D. S. Pezzack
Keyword(s):  
Nova Scotia ◽  
New Brunswick ◽  
Coastal Waters ◽  
Egg Production ◽  
Homarus Americanus ◽  
Bay Of Fundy ◽  
Georges Bank ◽  
Production Values ◽  
Large Numbers ◽  
Population Sizes

The relative abundance of berried female lobsters, Homarus americanus, and their contribution to total egg production in various areas of the Bay of Fundy and off southwestern Nova Scotia are estimated from sampling commercial and research cruise catches from traps. Concentrations of berried females occurred on Browns Bank, Georges Bank, and the New Brunswick side of the Bay of Fundy. To a lesser extent, berried females occurred in the coastal areas of southwestern Nova Scotia. Using a range of mortality values, a variety of population sizes were estimated from 1983 landings from which relative egg production values were calculated for each area. Lobsters from coastal waters of southwestern Nova Scotia combined with the Bay of Fundy were estimated to produce between 23 and 53% and those from the offshore Brown and eastern Georges Banks to produce between 47 and 77% of the region's total egg production. The results suggest that lobsters in each area are capable of producing large numbers of eggs. Where the resulting planktonic larvae settle as benthic juveniles is unclear.

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.

Egg production in the American lobster, Homarus americanus

2020 ◽  
pp. 267-290
Author(s):  
S.L. Waddy ◽  
D.E. Aiken
Keyword(s):  
Egg Production ◽  
Homarus Americanus ◽  
American Lobster

Changes in female lobster (Homarus americanus) size at maturity and implications for the lobster resource in Long Island Sound, Connecticut

2001 ◽  
Vol 52 (8) ◽  
pp. 1283 ◽  
Author(s):  
Donald F. Landers Jr ◽  
Milan Keser ◽  
Saul B. Saila
Keyword(s):  
Sexual Maturity ◽  
Egg Production ◽  
Long Island ◽  
Homarus Americanus ◽  
Long Island Sound ◽  
Female Size ◽  
Size At Maturity ◽  
Size At Sexual Maturity ◽  
Average Size ◽  
Island Sound

Population theory predicts that, under conditions of high age/size-specific mortality rates, individuals in highly exploited populations increase their fitness by decreasing size at sexual maturity, relative to less exploited populations. The benefit of early reproductive maturation is that individuals have a higher probability of surviving to maturity and contributing progeny to maintain the population. Empirical evidence, based on morphometric data from nearly 60 000 female lobsters collected since 1981, suggests that size at sexual maturity of female lobsters in Long Island Sound (USA) has recently decreased. Our findings were supported by decreases in average size and increases in abundance of egg-bearing females over the past two decades. Changes in female size at maturity and subsequent higher egg production may also help to explain the recent increase in lobster recruitment and landings. It is unclear whether these changes were caused by density-dependent factors related to the high exploitation of the species, by natural environmental factors (e.g. higher seawater temperatures), or a combination of the two.

Stock Definition, Recruitment Variability, and Larval Recruitment Processes in the American Lobster, Homarus americanus: A Review

1986 ◽  
Vol 43 (11) ◽  
pp. 2072-2084 ◽  
Author(s):  
G. P. Ennis
Keyword(s):  
Egg Production ◽  
Homarus Americanus ◽  
Ecosystem Change ◽  
American Lobster ◽  
Surface Currents ◽  
Larval Supply ◽  
Review Of The Literature ◽  
Larval Recruitment ◽  
Change Mechanisms ◽  
Standing Stocks

A review of the literature pertaining to stock definition, causes of variability in recruitment to standing stocks, and larval recruitment processes in the American lobster, Homarus americanus, is presented. Several stocks can be identified but their boundaries are indistinct. The areas are too large for consideration of any of the stocks as a single management unit. The bulk of annual landings is composed of recruitment to standing stocks since the preceding fishing season. Landings for all areas fluctuate and there is considerable variability in patterns of fluctuations between areas. Suggested causes of variability in recruitment include variation in temperature, variation in annual river discharge, fishery induced variability in egg production, man-made interruption in larval supply, and ecosystem change. Mechanisms that determine where larvae that originate in a given area eventually settle are uncertain. Literature on larval recruitment processes contains theories based on passive transport of larvae by surface currents and others based on interacting behavioral and hydrographic mechanisms that may enable larvae to maintain position near parental grounds.

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