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.

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.

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.

Fall and Spring Preplant Herbicide Applications Influence Spring Emergence of Glyphosate-Resistant Horseweed (Conyza canadensis)

2010 ◽  
Vol 24 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Vince M. Davis ◽  
Greg R. Kruger ◽  
Bryan G. Young ◽  
William G. Johnson
Keyword(s):  
Early Spring ◽  
Late Spring ◽  
Conyza Canadensis ◽  
No Till ◽  
Early Fall ◽  
Winter Annual ◽  
Winter Annual Weeds ◽  
Annual Weeds ◽  
Spring Emergence ◽  
Residual Control

Horseweed (Conyza canadensis) is a common weed in no-till crop production systems. It is problematic because of the frequent occurrence of biotypes resistant to glyphosate and acetolactate synthase (ALS)-inhibiting herbicides and its ability to complete its life cycle as a winter or summer annual weed. Tactics to control horseweed while controlling other winter annual weeds routinely fail; herbicide application timing and spring emergence patterns of horseweed may be responsible. The objectives of this experiment were to (1) determine the influence of fall and spring herbicides with and without soil residual horseweed activity on spring-emerging glyphosate-resistant (GR) horseweed density and (2) evaluate the efficacy and persistence of saflufenacil on GR horseweed. Field studies were conducted in southern Indiana and Illinois from fall 2006 to summer 2007 and repeated in 2007 to 2008. Six preplant herbicide treatments were applied at four application timings: early fall, late fall, early spring, and late spring. Horseweed plants were counted every 2 wk following the first spring application until the first week of July. Horseweed almost exclusively emerged in the spring at both locations. Spring horseweed emergence was higher when 2,4-D + glyphosate was fall-applied and controlled other winter annual weeds. With fall-applied 2,4-D + glyphosate, over 90% of the peak horseweed density was observed before April 25. In contrast, only 25% of the peak horseweed density was observed in the untreated check by April 25. Starting from the initiation of horseweed emergence in late March, chlorimuron + tribenuron applied early fall or early spring, and spring-applied saflufenacil at 100 g ai/ha provided greater than 90% horseweed control for 12 wk. Early spring–applied saflufenacil at 50 g ai/ha provided 8 wk of greater than 90% residual control, and early spring–applied simazine provided 6 wk of greater than 90% control. When applied in late spring, saflufenacil was the only herbicide treatment that reduced horseweed densities by greater than 90% compared to 2,4-D + glyphosate. We concluded from this research that fall applications of nonresidual herbicides can increase the rate and density of spring emerging horseweed. In addition, spring-applied saflufenacil provides no-till producers with a new preplant herbicide for foliar and residual control of glyphosate- and ALS-resistant horseweed.

Trapping female cabbage root flies (Delia radicum (L.)) (Diptera: Anthomyiidae) with allylisothiocyanate-Baited traps

1982 ◽  
Vol 72 (1) ◽  
pp. 165-173 ◽  
Author(s):  
S. Finch ◽  
G. Skinner
Keyword(s):  
Field Experiments ◽  
Liquid Paraffin ◽  
Point Sources ◽  
Delia Radicum ◽  
Brassica Crops ◽  
Baited Traps ◽  
Odour Plume

AbstractField experiments in England with traps baited with allylisothiocyanate (ANCS) showed that females of Delia radicum (L.) were distributed more or less evenly through established brassica crops. Reducing the quantity of ANCS released from the traps either by diluting the concentrate with liquid paraffin or by presenting the concentrate in Wädenswil dispensers reduced the numbers of females caught. There was no indication that ANCS became repellent, even when released at a rate of 24 ml/trap per day. For maximum effectiveness, the ANCS dispenser had to be placed at the centre rather than at the edge of the trap. Attempts to make traps more effective by releasing the ANCS from several point sources around a trap, in the hope that this broader odour plume would ‘ attract ’ more flies, were unsuccessful. The ANCS-baited trap had an effective zone only 5 m in radius.

Effect of certain monounsaturated dodecene and tetradecene acetates and alcohols on electroantennogram response and pheromone-mediated trap catch of the obliquebanded leafroller

2006 ◽  
Vol 138 (2) ◽  
pp. 218-227 ◽  
Author(s):  
R.M. Trimble ◽  
Ashraf M. El-Sayed
Keyword(s):  
Short Distance ◽  
Choristoneura Rosaceana ◽  
Inhibiting Activity ◽  
Trap Catch ◽  
Obliquebanded Leafroller ◽  
Baited Traps ◽  
Tetradecenyl Acetate ◽  
Pheromone Compound ◽  
Attraction Inhibitor ◽  
Stimulation Of

AbstractThe effect of certain monounsaturated dodecene and tetradecene acetates and alcohols on electroantennogram (EAG) response and pheromone-mediated trap catch was examined in male obliquebanded leafroller moths, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae). The stimulation of antennae with 0.1 ng of (Z)-11-tetradecenyl acetate (Z11-14:Ac), the major pheromone compound of this species, elicited an EAG response. The use of 1 ng of (Z)-9-tetradecenyl acetate (Z9-14:Ac) or (E)-9-tetradecenyl acetate (E9-14:Ac) or 10 ng of (Z)-9-dodecenyl acetate (Z9-12:Ac) or (E)-9-dodecenyl acetate (E9-12:Ac) was required to elicit a response. One hundred nanograms of (E)-9-tetradecenol (E9-14:OH) were required to elicit a response from antennae. The stimulation of antennae with up to 100 ng of (Z)-9-tetradecenol (Z9-14:OH) did not elicit a response. The addition of 0.1 mg of Z9-12:Ac to 1 mg of synthetic C. rosaceana pheromone consisting of a 100:2:1.5:1 blend of Z11-14:Ac, (E)-11-tetradecenyl acetate, (Z)-11-tetradecenol, and (Z)-11-tetradecenal reduced the capture of moths in pheromone-baited traps by more than 72%. Trap catch was reduced by more than 90% by the addition of 0.01 mg of Z9-14:Ac or E9-14:Ac to 1 mg of C. rosaceana pheromone. There was no detectable reduction in trap catch when 1 mg of E9-12:Ac, Z9-14:OH, or E9-14:OH was added to 1 mg of C. rosaceana pheromone. There was a greater than 95% reduction in trap catch when sources of Z9- or E9-12:Ac were mounted at the entrances to traps, 10 cm from the pheromone source. Trap catch was not affected by placing sources of Z9- or E9-14:Ac at trap entrances. Four 1 or 10 mg sources of E9-14:Ac placed 1 m from a trap did not affect the number of male C. rosaceana captured. The study demonstrates that although a compound may have profound attraction inhibiting activity when mixed directly with C. rosaceana pheromone, this activity may be lost if the inhibitor is emitted a short distance from the pheromone. The study also demonstrates that a potent attraction inhibitor such as E9-14:Ac does not repel C. rosaceana males and must be present along with pheromone to affect the behavior of this species.

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.

Nearshore currents and beach topography, Martinique Beach, Nova Scotia

1977 ◽  
Vol 14 (8) ◽  
pp. 1906-1915 ◽  
Author(s):  
J. R. Keeley
Keyword(s):  
Nova Scotia ◽  
Theoretical Model ◽  
Sediment Transport ◽  
Wind Direction ◽  
Seasonal Changes ◽  
Late Spring ◽  
Beach Profile ◽  
Storm Waves ◽  
Longshore Sediment Transport ◽  
Subsequent Disappearance

A series of profiles across Martinique Beach, Nova Scotia, surveyed at monthly intervals between April and October, 1974, showed the formation and subsequent disappearance of large cuspate projections on the beach face. A theoretical model of the distribution of longshore currents on the beach was used to predict the expected positions of convergences and divergences in the longshore sediment transport. The observed projections were found to occur in positions of convergence of waves generated by the southeasterly winds, dominant in the late spring. The disappearance of the cusps was associaled with the seasonal veering of wind direction to the southwest as summer advanced.The size of the seasonal changes in beach profile suggests that the morphology of Martinique Beach is controlled primarily by storm waves.

LIFE CYCLE AND MORTALITY OF PISSODES TERMINALIS (COLEOPTERA: CURCULIONIDAE) IN LODGEPOLE PINE

1998 ◽  
Vol 130 (4) ◽  
pp. 387-397 ◽  
Author(s):  
David W. Langor ◽  
Daryl J.M. Williams
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Late Spring ◽  
Cold Temperatures ◽  
Larval Instars ◽  
Complete Development ◽  
Early Fall ◽  
New Generation

AbstractThe seasonal life history and mortality of the lodgepole terminal weevil, Pissodes terminalis Hopping (Coleoptera: Curculionidae), were investigated in young lodgepole pine, Pinus contorta Douglas var. latifolia Engelmann (Pinaceae), at three sites in west-central Alberta. Flight was monitored with traps. Development and mortality of all stages were investigated by dissecting infested leaders biweekly from late spring to early fall. Two years were required for P. terminalis to complete its life cycle, and generations overlapped. Overwintered adults emerged from the duff and commenced flight in late May, with a peak in mid-June. Eggs were present from mid-June to late July. There were four larval instars. The first two instars fed only in the phloem. Third and fourth larval instars eventually entered the pith to continue feeding, overwinter, and complete development the following spring. The new generation of adults emerged between mid-July and early August, fed on new shoots for several weeks, and overwintered in the duff. Adults have an obligatory diapause and did not reproduce until after winter. Fourth larval instars suffered the highest mortality. The major attributable cause of mortality was resinosis among eggs and young larvae and cold temperatures during the winter among mature larvae. Pathogens caused little mortality. Six species of parasitoids were collected.

Distribution of ichthyophonus hoferi (Mastigomycotina: ichthyophonales) in yellowtail flounder, Limanda ferruginea, from the Nova Scotia Shelf, Canada

1992 ◽  
Vol 72 (3) ◽  
pp. 669-674 ◽  
Author(s):  
Thomas G. Rand
Keyword(s):  
Nova Scotia ◽  
Seasonal Cycle ◽  
Distribution Patterns ◽  
Early Summer ◽  
Seasonal Distribution ◽  
Marine Fishes ◽  
Infection Prevalence ◽  
Yellowtail Flounder ◽  
Limanda Ferruginea ◽  
Early Fall

A survey was conducted from 1986 to 1987 to determine the spatial and seasonal distribution patterns of Ichthyophonus hoferi Plehn & Mulsow, 1911 in marine fishes, especially yellowtail flounder, Limanda ferruginea, from the Nova Scotia shelf, Canada. Ichthyophonus hoferi was found in 56 of 6759 (0·83%) yellowtail flounder, in one of 613 (0·16%) haddock, Melanogrammus aelgefinus, but in none of the other 1485 fishes representing seven species sampled from this area. Within the yellowtail flounder population, the fungus was distributed in patchy manner with infection prevalence ranging from 0·4% at Banquereau Bank to about 13% at Brown's Bank. Infection prevalence was the same in both the male and female flounder. There was no apparent seasonal cycle in infection, although pathogen recruitment into L. ferruginea was from early summer through to early fall months.

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