Neustonic postlarval American lobsters, Homarus americanus, in the western Gulf of Maine: spatial and interannual variations

2000 ◽  
Vol 57 (4) ◽  
pp. 755-765 ◽  
Author(s):  
Lewis S Incze ◽  
Peter Aas ◽  
Terri Ainaire ◽  
Marcia Bowen
Keyword(s):  
New Hampshire ◽  
Gulf Of Maine ◽  
Stage Iv ◽  
Homarus Americanus ◽  
Seasonal Abundance ◽  
Interannual Variations ◽  
Distributed Source ◽  
High Recruitment ◽  
Benthic Population

We examined the seasonal abundance of postlarval (PL) (stage IV) American lobsters, Homarus americanus, from neuston samples from 1989 to 1995 at Johns Bay, Maine, and Seabrook, New Hampshire, located 150 km apart in the western Gulf of Maine. The postlarval season at these sites began between approximately days of the year 180 and 210 and ranged from about 35 to 70 days in duration. Within years, start and end dates were similar for the two sites. Maximum concentrations from single tows exceeded 100 PL·1000 m-2, but 85% or more of the positive tows had concentrations <15 PL·1000 m-2 and more than half had <5 PL·1000 m-2. These concentrations occurred at high levels of the stock, were the source for continued high recruitment in the 1990s, and thereby form a benchmark for future measurements. Only one of the seven years showed a major decline in seasonal abundance, and it occurred at both sites. Of the remaining years, three had nearly identical integrated abundances at both sites (approximately 200 PL· 1000 m-2·year-1). A survey in the western Gulf of Maine caught postlarvae out to 56 km offshore at concentrations similar to the coastal samples, indicating a broadly distributed source of potential recruits to the benthic population.

Quantitative relationships between postlarval production and benthic recruitment in lobsters, Homarus americanus

1997 ◽  
Vol 48 (8) ◽  
pp. 729 ◽  
Author(s):  
Lewis S. Incze ◽  
Richard A. Wahle ◽  
J. Stanley Cobb
Keyword(s):  
Rhode Island ◽  
Annual Variation ◽  
Gulf Of Maine ◽  
Homarus Americanus ◽  
Seasonal Abundance ◽  
Moult Cycle ◽  
American Lobster ◽  
Temperature Dependent ◽  
Dependent Growth ◽  
Island Sound

Relationships between lobster postlarval supply and benthic recruitment were evaluated within and between oceanographically distinct segments of the range of the American lobster. Postlarvae (PL) were sampled by neuston nets in western Rhode Island Sound and the western Gulf of Maine, USA, from June to September 1989–95. Benthic lobsters were sampled in sublittoral cobble habitat by using a diver-operated airlift at the end of the settlement season. Average annual recruitment densities of young-of-year (YOY) lobsters ranged from 0.3 to 1.7 m-2. YOY recruitment was positively correlated between areas. Integrated seasonal abundance of postlarvae was often much greater in Rhode Island than Maine, but production estimates (PL 1000 m-2 season-1), calculated from moult cycle stages and temperature-dependent growth rates, differed by a factor of <0.5. PL production was positively correlated between areas and explained ≥81% of the annual variation in recruitment in each area and 90% for the two areas combined. In Maine, among-site differences in YOY recruitment persisted for a year after settlement and then began to lessen, at least in part because larger individuals moved into areas of initially lower recruitment

Dispersal of Homarus americanus Larvae in the Gulf of Maine from Browns Bank

1988 ◽  
Vol 45 (3) ◽  
pp. 416-425 ◽  
Author(s):  
Gareth C. Harding ◽  
Ronald W. Trites
Keyword(s):  
Nova Scotia ◽  
Gulf Of Maine ◽  
Stage Iv ◽  
Homarus Americanus ◽  
Seasonal Migration ◽  
Ecological Traits ◽  
Growth And Survival ◽  
Larval Recruitment ◽  
Surface Drifter ◽  
Planktotrophic Larvae

Studies of larval lobster (Homarus americanus) distribution off southwestern Nova Scotia during the summers of 1977 and 1978, were used to estimate an average larval recruitment or production of 1918 and 5284 stage IV lobsters per square kilometre per year inshore and offshore, respectively. Results indicate that the offshore may contribute up to 97% of the larval recruits for the entire southwestern Nova Scotia region. Current patterns and velocities of 3–16 cm∙s−1 were estimated from surface drifter returns within the Gulf of Maine. Limits of larval dispersion are estimated from surface currents in the region and the physiological and ecological traits of the larval lobster. Offshore lobsters could make an important contribution to recruitment not only off southwestern Nova Scotia but in the entire eastern sector of the Gulf of Maine to Casco Bay. Larval dispersal provides another line of evidence that the Gulf of Maine area represents one lobster recruitment center. Our results are consistent with the idea that ontogenic seasonal migration of female lobsters has evolved to locate planktotrophic larvae in warmer shoal areas where growth and survival is optimal and from which ocean currents subsequently disperse a large portion of these larvae to settle over highly productive juvenile grounds.

Predicting bycatch hotspots based on suitable habitat derived from fishery-independent data

2020 ◽  
Vol 641 ◽  
pp. 159-175
Author(s):  
J Runnebaum ◽  
KR Tanaka ◽  
L Guan ◽  
J Cao ◽  
L O’Brien ◽  
...  
Keyword(s):  
Habitat Suitability ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Gulf Of Maine ◽  
Homarus Americanus ◽  
Management Tool ◽  
American Lobster ◽  
Suitable Habitat ◽  
Climate Conditions ◽  
Suitability Index

Bycatch remains a global problem in managing sustainable fisheries. A critical aspect of management is understanding the timing and spatial extent of bycatch. Fisheries management often relies on observed bycatch data, which are not always available due to a lack of reporting or observer coverage. Alternatively, analyzing the overlap in suitable habitat for the target and non-target species can provide a spatial management tool to understand where bycatch interactions are likely to occur. Potential bycatch hotspots based on suitable habitat were predicted for cusk Brosme brosme incidentally caught in the Gulf of Maine American lobster Homarus americanus fishery. Data from multiple fisheries-independent surveys were combined in a delta-generalized linear mixed model to generate spatially explicit density estimates for use in an independent habitat suitability index. The habitat suitability indices for American lobster and cusk were then compared to predict potential bycatch hotspot locations. Suitable habitat for American lobster has increased between 1980 and 2013 while suitable habitat for cusk decreased throughout most of the Gulf of Maine, except for Georges Basin and the Great South Channel. The proportion of overlap in suitable habitat varied interannually but decreased slightly in the spring and remained relatively stable in the fall over the time series. As Gulf of Maine temperatures continue to increase, the interactions between American lobster and cusk are predicted to decline as cusk habitat continues to constrict. This framework can contribute to fisheries managers’ understanding of changes in habitat overlap as climate conditions continue to change and alter where bycatch interactions could occur.

Effect of Temperature on the Behavior of Stage IV American Lobster (Homarus americanus) Larvae

2015 ◽  
Vol 34 (2) ◽  
pp. 545-554 ◽  
Author(s):  
Melanie Chiasson ◽  
Gilles Miron ◽  
Dounia Daoud ◽  
Martin D. Mallet
Keyword(s):  
Stage Iv ◽  
Homarus Americanus ◽  
Effect Of Temperature ◽  
American Lobster

Larval lobster (Homarus americanus) distribution and drift in the vicinity of the Gulf of Maine offshore banks and their probable origins

2005 ◽  
Vol 14 (2) ◽  
pp. 112-137 ◽  
Author(s):  
G. C. HARDING ◽  
K. F. DRINKWATER ◽  
C. G. HANNAH ◽  
J. D. PRINGLE ◽  
J. PRENA ◽  
...  
Keyword(s):  
Gulf Of Maine ◽  
Homarus Americanus

Ecology and Growth of Postlarval and Juvenile Lobster, Homarus americanus, off Îles de la Madeleine (Quebec)

1987 ◽  
Vol 44 (11) ◽  
pp. 1855-1869 ◽  
Author(s):  
Christiane Hudon
Keyword(s):  
Growth Factor ◽  
Size Structure ◽  
Stage Iv ◽  
High Growth ◽  
Homarus Americanus ◽  
Fine Tuning ◽  
Mean Size ◽  
Density And Biomass ◽  
Rocky Bottoms ◽  
La Madeleine

Lobsters, Homarus americanus were studied in various habitats off Îles de la Madeleine, Quebec, from June to October 1985. Density, biomass, and size structure were estimated quantitatively using underwater corrals (40 m2) on rocky bottoms or transects (200 m2) on sandy bottoms and eelgrass beds. On the basis of behavioural observations during capture, lobsters were divided into postlarvae (<25 mm carapace length, CL), juveniles (25–76 mm CL), and adults (>76 mm CL). Density, biomass, and size structure were closely related to the coarseness of the bottom. Density and biomass were greater and mean size was larger on algae-covered boulders than on bare stones. Postlarval and juvenile lobsters were most numerous on shallow rocky bottoms where high densities (0.8–3.8 ind∙m−2) of small lobsters (mean size from 23.8 to 35.5 mm CL) were captured. Low density of juveniles and adults occurred on sand covered with eelgrass. No resident lobsters were found on bare sand. Temporal variation of postlarval density was synchronous at the three stations investigated. Postlarval density decreased during the summer until the settlement of planktonic postlarvae in mid-August. Moulting activity occurred throughout the summer, with a peak in early July. Mean size values for stages V–XIV were fitted to the cumulated size distribution and were used to calculate the percent increment for each moult stage (growth factor) and the expected duration of each stage. The 2-mo duration of the stage IV settlement period could result in a size range of 6–21 mm CL (mean size 14.5 mm CL, stage VIII) for a cohort by the end of its first season of benthic growth. The transition from planktonic to benthic life was characterized by a decrease of the growth factor at stage V, which was subsequently compensated at stages VI and VII by high growth factor values. In the first three growth seasons, spring and summer moults exhibit higher growth factor values than fall moults. These seasonal variations result in regular oscillations of the growth factor dampening progressively between stages V and XIV, instead of the smooth decline hypothesized in previous studies. A combination of factors, such as cryptic behaviour, high substrate selectivity, gradual settlement over the late summer months, and variability in growth factor, reflect the very fine tuning of the lobster's early benthic life stages to the constraints of its physical environment.

scholarly journals Temporal variability, sources, and sinks of C<sub>1</sub>-C<sub>5</sub> alkyl nitrates in coastal New England

2010 ◽  
Vol 10 (4) ◽  
pp. 1865-1883 ◽  
Author(s):  
R. S. Russo ◽  
Y. Zhou ◽  
K. B. Haase ◽  
O. W. Wingenter ◽  
E. K. Frinak ◽  
...  
Keyword(s):  
New England ◽  
New Hampshire ◽  
Dry Deposition ◽  
Gulf Of Maine ◽  
Ambient Air ◽  
Early Morning ◽  
Secondary Source ◽  
Alkyl Nitrates ◽  
Mixing Ratios ◽  
Alkyl Nitrate

Abstract. Seven C1-C5 alkyl nitrates were measured both on the mainland and off the coast of New Hampshire using gas chromatographic techniques. Five separate data sets are presented to characterize the seasonal and diurnal trends and the major sources and loss processes of these compounds. Based on in situ measurements conducted at the University of New Hampshire (UNH) Atmospheric Observing Station at Thompson Farm (TF) located in southeast NH during winter (January–February) 2002, summer (June–August) 2002, summer (July–August) 2004, and on daily canister samples collected at midday from January 2004–February 2008, the median total alkyl nitrate mixing ratio (ΣRONO2) was 23–25 pptv in winter and 14–16 pptv in summer. During summers 2002 and 2004, MeONO2 decreased overnight and reached minimum hourly average mixing ratios in the early morning. Comparison with wind speed and trace gas trends suggested that dry deposition contributed to the early morning MeONO2 minimum which is a previously unaccounted for removal mechanism. The mean dry deposition rate and velocity of MeONO2 was estimated to be −0.5 nmol m−2 hr−1 and 0.13 cm s−1, respectively. Results from ambient air and surface seawater measurements made onboard the NOAA R/V Ronald H. Brown in the Gulf of Maine during the 2002 New England Air Quality Study and from ambient canister samples collected throughout the Great Bay estuary in August 2003 are also presented. Comparisons between the alkyl nitrate trends with anthropogenic and marine tracers suggest that a marine source of alkyl nitrates is not significant in coastal New England. Given the apparent prominence of a secondary source, comparisons between observed and predicted alkyl nitrate/parent hydrocarbon ratios were made which demonstrated that background mixing ratios have a continuous and prevalent influence on the alkyl nitrate distribution.

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