The catchability of large American lobsters (Homarus americanus) from diving and trapping studies off Grand Manan Island, Canadian Maritimes

2006 ◽  
Vol 63 (9) ◽  
pp. 1925-1933 ◽  
Author(s):  
M J Tremblay ◽  
S J Smith ◽  
D A Robichaud ◽  
P Lawton
Keyword(s):  
Generalized Linear Models ◽  
Carapace Length ◽  
Linear Models ◽  
Size Range ◽  
Late Summer ◽  
Homarus Americanus ◽  
Agonistic Interactions ◽  
Size Groups ◽  
Early Fall ◽  
Catch Rates

Catchability (q) in traps was estimated for American lobsters (Homarus americanus) in Flagg Cove, off Grand Manan Island (New Brunswick, Canada), where large females (>100 mm carapace length (CL)) aggregate in late summer and early fall. In 2001 and 2002, diver surveys were used to estimate lobster density, and traps were then deployed to obtain catch rates. Bayesian generalized linear models were fit to the densities of different size groups (81–100, 101–130, 131–160, and >160 mm CL) of ovigerous females, non-ovigerous females, and males. Catchability was strongly affected by year. Differences in q due to sex and size for ovigerous females, non-ovigerous females, and males were apparent but were not consistent between years. Size was not an important factor for the catchability of lobsters between 81 and 160 mm CL. In comparison with lobsters of a similar size in other areas, Flagg Cove lobsters in the size range of 81–100 mm CL were less catchable. We hypothesize that this resulted from the high densities and larger sizes of lobsters in Flagg Cove, which likely lead to increased agonistic interactions and reduced entry of lobsters into traps.

Size–Maturity Relationships and Related Observations in Newfoundland Populations of the Lobster (Homarus americanus)

1980 ◽  
Vol 37 (6) ◽  
pp. 945-956 ◽  
Author(s):  
G. P. Ennis
Keyword(s):  
Carapace Length ◽  
Size Range ◽  
Sex Ratios ◽  
Weight Ratio ◽  
Homarus Americanus ◽  
Spawning Season ◽  
Length Ratio ◽  
Maturity Indices

Female maturity ogives for five Newfoundland populations of the lobster (Homarus americanus) gave 50% maturities ranging from 71- to 76-mm carapace length. Sizes at which distinct inflections (indicating onset of maturity) and asymptotes (indicating 100% mature) are present in the abdomen width/carapace length ratio vs. carapace length relationships coincide with the smallest ovigerous and largest immature specimens, respectively, observed in those particular samples. Inflection in the crusher claw weight/whole weight ratio vs. carapace length relationships (used in this paper to indicate onset of maturity in males) occurred at larger sizes than inflections in the abdomen width/carapace length ratios of females.The percentage of nonovigerous females that spawn in a given year generally increases with increasing size. The highest percentage of nonovigerous females tagged with sphyrion tags prior to the spawning season that were ovigerous when recaptured 10–12 mo later was 83.8%. The percentage of ovigerous females with new shells (i.e. molted and spawned in same year) varied between areas and years and ranged from 0 to 38.5% of the total number of ovigerous females in fall samples. The percentage of ovigerous females in samples also varied between areas and years and ranged from 2.6 to 30.4% of the total number of females greater than the size at 50% maturity. In general a greater percentage of females was ovigerous at sizes between the size at 50% maturity and 80 mm (largest subcommercial size) than at commercial sizes.In a sample of nonovigerous females, the size range at which 50% were fertilized (76–80 mm) coincided closely with the size at 50% maturity (75 mm) for the area.At subcommercial sizes (< 81 mm) the sexes were approximately equally represented in fall trap-caught samples but females heavily outnumbered males in diver-caught samples taken over the same period. At commercial sizes, however, males heavily outnumbered females in the trap-caught samples while in diver-caught samples the sexes were equally represented.Key words: lobster (Homarus americanus), maturity ogives, maturity indices, percent ovigerous, sex ratios

The life histories of north-temperate populations of the crayfish Cambarus robustus and Cambarus bartoni

1985 ◽  
Vol 63 (10) ◽  
pp. 2313-2322 ◽  
Author(s):  
Premysl Hamr ◽  
Michael Berrill
Keyword(s):  
Life History ◽  
Life Histories ◽  
Carapace Length ◽  
Late Summer ◽  
Temperate Climate ◽  
Free Living ◽  
Southern Ontario ◽  
The Third ◽  
Early Fall ◽  
First Time

The life histories of the crayfish Cambarus robustus and Cambarus bartoni were studied in the Kawartha Lakes region of southern Ontario. There were marked differences in their breeding and molting cycles compared with the familiar pattern of the Orconectes species of this region. Egg extrusion occurred later (July in C. robustus, June in C. bartoni), and juveniles therefore did not become free living until late summer or early fall. With little growing time in their first summer, they measured only 5–10 mm in carapace length (CPL) before growth ceased for the winter. At the end of their second summer the still immature crayfish measured 17–26 mm CPL in C. robustus and 13–20 mm CPL in C. bartoni. Maturity was therefore not attained until the end of the third summer, when most C. robustus matured at 34–45 mm CPL and C. bartoni at 25–30 mm CPL. The majority of individuals apparently reproduced for the first time during their fourth summer; a few apparently survived into another summer, reaching carapace lengths greater than 50 mm in C. robustus and 30 mm in C. bartoni. In males of both species, form 1 and form 2 occur throughout the summer. Although lacking the synchrony of Orconectes species, breeding and molting activities are still confined to the period between April and October. The timing of the life-history events observed in these two Cambarus species may be adaptations to seasonal stresses of the swift water environments that these species inhabit as well as to the relative harshness of the northern temperate climate.

scholarly journals Recruitment indices of European hake, Merluccius merluccius (Linnaeus 1758), in the Northwest Mediterranean based on landings from bottom-trawl multispecies fisheries

2004 ◽  
Vol 61 (5) ◽  
pp. 760-773 ◽  
Author(s):  
Raquel Goñi ◽  
Sara Adlerstein ◽  
Federico Alvarez ◽  
Mariano García ◽  
Pilar Sánchez ◽  
...  
Keyword(s):  
Linear Models ◽  
Stock Assessment ◽  
Late Summer ◽  
Bottom Trawl ◽  
Multivariate Techniques ◽  
Merluccius Merluccius ◽  
Commercial Catch ◽  
Size Category ◽  
Catch Rates ◽  
Species Proportions

Abstract Temporal and spatial variation in Merluccius merluccius recruitment in the Northwest Mediterranean is examined, and recruitment indices are derived from monthly M. merluccius catch rates of four bottom-trawl fleets operating in Spanish and Italian waters during the period 1991–1999. Where M. merluccius catches were not recorded by size category, multivariate techniques were applied to species proportions in order to identify catch records most representative of recruit abundance. Selected catch rates were analysed by generalized linear models (GLMs) to estimate recruitment indices. The GLMs explain large proportions of the variation in recruit abundance (50–84%) and indicate significant annual and seasonal variation in recruitment strength. Vessel was by far the most important factor affecting catch rates of recruits, stressing the need to account for vessel characteristics when analysing commercial catch data for stock assessment. Seasonal patterns of recruitment reveal similarities among the study areas and interannual variations within areas. One major recruitment peak was identified in each area during either spring/summer or late summer/winter. In most areas, recruitment between 1991 and 1999 seemed to decline, but this could not be confirmed owing to high interannual variability. The coherence of annual fluctuations in recruitment indices with those of MEDITS surveys supports the present results.

Growth Per Moult of Tagged Lobsters (Homarus americanus) in Bonavista Bay, Newfoundland

1972 ◽  
Vol 29 (2) ◽  
pp. 143-148 ◽  
Author(s):  
G. P. Ennis
Keyword(s):  
Carapace Length ◽  
Size Range ◽  
Homarus Americanus ◽  
Total Weight ◽  
Growth Studies ◽  
Field Samples ◽  
Length Increment ◽  
Significant Change

The suitability of the sphyrion tag for lobster growth studies is demonstrated by comparing growth of ferromagnetic- and sphyrion-tagged lobsters. Carapace length and total weight increments in one moult of 54 males (52–92-mm carapace length) tagged with sphyrion tags averaged 11.4 mm (15.7%) and 185.9 g (60.8%). For 56 females 57–89-mm carapace length they averaged 9.8 mm (13.3%) and 136.3 g (42.5%). Differences in growth per moult between sexes increased with size. For both sexes percent carapace length increment decreased with increase in carapace length but more rapidly for females. Carapace length increment increased with increasing carapace length for males, but for females there was no significant change over the size range considered. Incidence of moulting for sphyrion-tagged lobsters was 83.1% and comparable with an observed estimate (85.2%) from field samples obtained shortly after the moulting season.

Lobster (Homarus americanus) catchability in different habitats in late spring and early fall

2001 ◽  
Vol 52 (8) ◽  
pp. 1321 ◽  
Author(s):  
M. John Tremblay ◽  
Stephen J. Smith
Keyword(s):  
Nova Scotia ◽  
Homarus Americanus ◽  
Late Spring ◽  
Trap Catch ◽  
Loglinear Models ◽  
Model Based ◽  
Baited Traps ◽  
Odour Plume ◽  
Early Fall ◽  
Catch Rates

The effects of habitat and season on the catchability of lobsters (Homarus americanus) in baited traps were studied in September and June in Lobster Bay, Nova Scotia, by means of dive censuses followed by trapping. Moderate boulder cover characterized one site; two others had low relief (sand or mud dominated). Poisson loglinear models of the data were used to evaluate the effect of site, size, and sex on lobster catchability (q). This approach generates model-based estimates of q in units of square metres per trap. In both seasons lobster density (all sizes > 50 mm) at the two low-relief sites (means of 15–18 per 300-m2 transect) was lower than that at the moderate-boulder site (means of 25–26 per transect), but trap catch rates were higher at low-relief sites. The models confirmed that lobster catchability was lower at the moderate-boulder site. Potential explanations include more shelter-seeking behaviour at the moderate-boulder site and hydrodynamic differences affecting the bait odour plume. The largest difference between seasons was higher q’s in spring for prerecruit sizes (71–80 mm CL) at all sites, perhaps due to fishery removals of larger sizes. The results have implications for lobster assessments and the planning of trap surveys of abundance.

scholarly journals Trends in trawl and purse seine catch rates in the north-eastern Mediterranean

2008 ◽  
Vol 9 (1) ◽  
pp. 49 ◽  
Author(s):  
A. MACHIAS ◽  
K.I. STERGIOU ◽  
S. SOMARAKIS ◽  
V.S. KARPOUZI ◽  
A. KAPANTAGAKIS
Keyword(s):  
Trend Analysis ◽  
Linear Models ◽  
Eastern Mediterranean ◽  
Fishing Effort ◽  
The North ◽  
North Eastern ◽  
Size Groups ◽  
North Aegean ◽  
Catch Rates ◽  
Catch Per Effort

Data on fishing effort expressed in vessel days at sea and corresponding landing/day for a large number of species have been collected by the Institute of Marine Biological Resources (IMBR) since the second half of 1995. Data were collected over a grid of 21 stations throughout the Greek seas. In the present study we analyzed the monthly days at sea as well as catch per day for trawlers and purse seiners from 1996 to 2000, by general linear models and trend analysis. The following vessel size groups per gear were considered: (a) trawlers smaller and larger than 20m; (b) purse-seiners smaller and larger than 15m. Collected data were also aggregated for five fishing sub-areas: the North Aegean, the Central Aegean, the South Aegean, Cretan waters and the Ionian Sea. Trend analysis of landing/day time series indicated that demersal and pelagic resources are declining in the main fishing grounds. Declining landing/day trends are regarded as indicators of overfishing, especially in the light of the fact that high catch rates are maintained by fishing in ‘hot spots’. The results of the present analysis provide, for the first time, important information on the sustainability of the fisheries in the north-eastern Mediterranean, an area characterized by a complete lack of accurate long-term data on effort and catch per effort

The Growth Rate of the American Lobster (Homarus americanus)

1953 ◽  
Vol 10 (7) ◽  
pp. 371-412 ◽  
Author(s):  
D. G. Wilder
Keyword(s):  
Carapace Length ◽  
Growing Season ◽  
Homarus Americanus ◽  
American Lobster ◽  
Maritime Provinces ◽  
Larval Stages ◽  
Total Length ◽  
Straight Line ◽  
Size Groups ◽  
Stage 1

Carapace measurements of lobster larvae caught in the western part of Northumberland Strait showed that in this area the natural growth in length per moult is 34.4 per cent from stage 1 to stage 2, 31.8 per cent from stage 2 to 3, and 30.3 per cent from stage 3 to 4. The seasonal distribution of the first four larval stages was determined from plankton tows made continuously from mid-June to late September each year from 1948 to 1952. To determine natural annual growth, lobsters of 15 to 25 cm., total length, were sorted into five or six size groups and were distinctively marked by means of holes punched through the tail fan. These were liberated on six widely separated fishing grounds in the Maritime Provinces. Recoveries of these marked lobsters four to twelve months after release showed that in the southern Gulf of St. Lawrence, 15- to 20-cm. lobsters grew 8 to 9 mm. (13 to 15 per cent) in carapace length, 22 to 25 mm. (13 to 14 per cent) in total length and 80 to 95 grams (45 to 53 per cent) in weight. In southern Nova Scotia and Grand Manan 20- to 25-cm. lobsters grew 10 to 12 mm. (13 to 15 per cent) in carapace length, 27 to 34 mm. (12 to 15 per cent) in total length and 170 to 220 grams (43 to 54 per cent) in weight. From the carapace length of 4th-stage larvae and straight-line equations relating carapace length before moulting and carapace length after moulting, the average carapace lengths of lobsters in stages 5 to 20 were calculated. From observations and calculations on the growth per moult and moulting frequency, it is estimated that in the Northumberland Strait area lobsters reach a length of 14 cm. (51/2 in.) at the end of the fifth growing season (41/4 years old) and 24 cm. (91/2 in.) at the end of the ninth growing season (81/4 years).

Effect of Different Dentifrices, Bleaching with 35% Hydrogen Peroxide, and Red Wine on Surface Color and Roughness of Bovine Enamel

2020 ◽  
Vol 02 ◽  
Author(s):  
RM Garcia ◽  
WF Vieira-Junior ◽  
JD Theobaldo ◽  
NIP Pini ◽  
GM Ambrosano ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Generalized Linear Models ◽  
Repeated Measures ◽  
Red Wine ◽  
Linear Models ◽  
Artificial Saliva ◽  
Surface Color ◽  
Dental Bleaching ◽  
Surface Alteration ◽  
Bovine Enamel

Objective: To evaluate color and roughness of bovine enamel exposed to dentifrices, dental bleaching with 35% hydrogen peroxide (HP), and erosion/staining by red wine. Methods: Bovine enamel blocks were exposed to: artificial saliva (control), Oral-B Pro-Health (stannous fluoride with sodium fluoride, SF), Sensodyne Repair & Protect (bioactive glass, BG), Colgate Pro-Relief (arginine and calcium carbonate, AR), or Chitodent (chitosan, CHI). After toothpaste exposure, half (n=12) of the samples were bleached (35% HP), and the other half were not (n=12). The color (CIE L*a* b*, ΔE), surface roughness (Ra), and scanning electron microscopy were evaluated. Color and roughness were assessed at baseline, post-dentifrice and/or -dental bleaching, and after red wine. The data were subjected to analysis of variance (ANOVA) (ΔE) for repeated measures (Ra), followed by Tukey ́s test. The L*, a*, and b* values were analyzed by generalized linear models (a=0.05). Results: The HP promoted an increase in Ra values; however, the SF, BG, and AR did not enable this alteration. After red wine, all groups apart from SF (unbleached) showed increases in Ra values; SF and AR promoted decreases in L* values; AR demonstrated higher ΔE values, differing from the control; and CHI decreased the L* variation in the unbleached group. Conclusion: Dentifrices did not interfere with bleaching efficacy of 35% HP. However, dentifrices acted as a preventive agent against surface alteration from dental bleaching (BG, SF, and AR) or red wine (SF). Dentifrices can decrease (CHI) or increase (AR and SF) staining by red wine.

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