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The Magnuson-Stevens Fishery Conservation and Management Act mandates US fisheries minimize adverse effects of fishing on essential fish habitat (EFH). The Gulf of Maine (GoM) American lobster (Homarus americanus) fishery is the most valuable US fishery and can deploy more than three million traps annually. To date, the impact of this fishery on benthic EFH has not been addressed quantitatively. To evaluate the impact of the GoM lobster fishery on EFH, we incorporated lobster fishing effort into a model linking habitat susceptibility and recovery to area impacted by fishing gear: the Swept Area Seabed Impact model. Impact to EFH was localized along the coast and highest along midcoast Maine. Upwards of 13% of the benthos is in the process of recovery, but between 99.92% and 99.96% of initially affected habitat fully recovers. These estimates suggest that lobster fishing negligibly contributes to accumulation of EFH damage in the GoM due to the expansive area fished and the small footprint of each trap. Identifying areas of persistent impact is crucial in developing effective fisheries management for critical marine habitats. La Magnuson-Stevens Fishery Conservation and Management Act impose aux peches etats-uniennes de minimiser les effets nefastes de la peche sur les habitats essentiels du poisson (HEP). De toutes les peches aux Etats-Unis, la peche au homard (Homarus americanus) dans le golfe du Maine (GdM) est celle qui revet la plus grande valeur, plus de trois millions de pieges pouvant etre deployes annuellement dans le cadre de ces activites. A ce jour, l'incidence de cette peche sur les HEP benthiques n'a pas ete examinee de maniere quantitative. Afin d'evaluer l'incidence de la peche au homard dans le GdM sur les HEP, l'effort de peche au homard a ete integre dans un modele qui relie la susceptibilite et le retablissement des habitats a la superficie ayant subi des impacts des engins de peche : le modele d'impact sur la superficie balayee du fond marin. L'impact sur les HEP est concentre le long de la cote et est le plus grand le long du littoral central du Maine. Plus de 13 % du benthos est en cours de retablissement, mais de 99,92 % a 99,96 % des habitats initialement touches se retablissent completement. Ces estimations donnent a penser que la peche au homard a un effet negligeable sur l'accumulation de dommages aux HEP dans le GdM en raison de l'ampleur de la region exploitee et de la faible empreinte de chaque piege. La determination des zones d'impact persistant est d'importance cle pour la mise en place d'une gestion efficace de la peche dans le but de proteger les habitats marins essentiels., Introduction The Gulf of Maine (GoM) lobster (Homarus americanus) fishery is the most valuable fishery in the United States (MDMR 2019a; NMFS 2019). Over the past three decades, the annual [...]

It is well known in ecological studies that the choice of spatial scale can influence the possibility of detecting ecological patterns and the type of patterns observed. However, this has rarely been evaluated for fish stock-recruitment (SR) dynamics. Inappropriate scales may result in failure to identify possible SR relationships, especially for species with complicated life history and stock structure and locally generated recruitment. Using American lobster (Homarus americanus) in the Gulf of Maine (GOM) as an example, we tested the hypotheses that the SR relationship is detectable only at certain spatial scales and the functional SR relationships vary with spatial scales. We estimated the SR relationship separately for American lobster in the eastern and western GOM, which have strongly differing oceanographic conditions that may result in different suitable spatial scale and SR dynamics for lobster. We analyzed data of 11 different spatial scales using a Bayesian method. The model fit and performances in the posterior predictive assessment for the SR models were convexly related to the spatial scales. The functional SR relationships differed for different spatial scale. The SR parameter estimates are negatively or concavely related to the spatial scale. The best model was found at medium spatial scale for both the eastern and western GOM, and the scale differed between the eastern and western GOM, suggesting that optimal spatial scale might be process-related. We demonstrated that the choice of spatial scale directly affected the possibility of identifying the SR relationship, the estimation of SR parameters, the type of SR relationships, and the predictive abilities of the SR models. Il est bien etabli dans les etudes ecologiques que le choix de l'echelle spatiale peut influencer la possibilite de detection de motifs ecologiques et le type de motifs observe. Cela n'a toutefois que rarement ete evalue pour la dynamique de recrutement au stock (RS) des poissons. Un mauvais choix d'echelle peut se traduire par l'impossibilite de cerner les relations de RS possibles, en particulier pour les especes caracterisees par un cycle biologique et une structure de stock complexes et un recrutement local. En utilisant l'exemple du homard (Homarus americanus) dans le golfe du Maine (GOM), nous avons verifie les hypotheses voulant que la relation RS ne puisse etre detectee qu'a certaines echelles spatiales et que les relations RS fonctionnelles varient selon l'echelle spatiale. Nous avons estime separement les relations RS pour le homard dans les parties est et ouest du GOM, caracterisees par des conditions oceanographiques tres differentes pouvant se traduire par differentes echelles spatiales convenables et differentes dynamiques de RS pour les homards. Nous avons analyse des donnees de 11 echelles spatiales differentes a l'aide d'une methode bayesienne. Le calage et la performance des modeles dans l'evaluation predictive posterieure pour les modeles de RS presentaient une relation convexe avec les echelles spatiales. Les relations RS fonctionnelles variaient selon l'echelle spatiale. Les estimations des parametres de RS presentent une relation negative ou concave avec l'echelle spatiale. Le meilleur modele etait a une echelle spatiale intermediaire tant pour la partie est que pour la partie ouest du GOM, et l'echelle etait differente pour les deux regions, donnant a penser que l'echelle spatiale optimale pourrait etre liee au processus. Nous avons demontre que le choix de l'echelle spatiale a une incidence directe sur la possibilite d'etablir la relation RS, sur l'estimation des parametres de RS, sur le type de relations RS et sur les capacites predictives des modeles de RS. [Traduit par la Redaction], Introduction Patterns and scales have long been recognized as two of the most important issues in ecological studies (Levin 1992; Schneider 2001). Although often oversimplified, prevalent ways to make data [...]

We used remote sensing chlorophyll a concentration data, spring copepod abundance, and individual fish condition information to understand the annual recruitment variability of two neighboring haddock (Melanogrammus aeglefinus) stocks in the Gulf of Maine region. When we considered the full range of recruitment variability, the abundance of the copepods Calanus finmarchicus and Pseudocalanus spp. failed to explain the variation in survivor ratio in either stock. However, when we examined this relationship with subsets of the data, we found that Pseudocalanus spp. appears to have had an effect on survivor ratio. The full range of recruitment variability of the Georges Bank stock was found to correlate with the timing and size of the fall bloom the year before recruitment, which has been termed the parental condition hypothesis, suggesting that the fall bloom affects the condition of spawning adults and thus recruitment. The absence of a correlation between fall bloom and recruitment in the Gulf of Maine stock can be attributed to the difference in fall bloom frequency between the two stock areas. It appears that both parental condition and larval survival affect haddock recruitment; however, the relative impact of these effects depends on the contrasting nature of ecosystem environmental drivers. Nous avons utilise des donnees de teledetection sur les concentrations de chlorophylle a, l'abondance printaniere de copepodes et l'embonpoint individuel de poissons pour comprendre la variabilite annuelle de deux stocks voisins d'aiglefins (Melanogrammus aeglefinus) dans la region du golfe du Maine. Quand toute la fourchette de variabilite du recrutement etait prise en consideration, l'abondance des copepodes Calanus finmarchicus et Pseudocalanus spp. ne pouvait expliquer la variation des rapports de survivants dans l'un ou l'autre des stocks. Cependant, quand cette relation etait examinee a la lumiere de sousensembles de donnees, nous avons constate que Pseudocalanus spp. semble avoir un effet sur le rapport de survivants. La fourchette entiere de variabilite du recrutement du stock du banc de Georges etait correlee au moment et a la taille de la proliferation automnale de l'annee precedant le recrutement, ce qui a ete designe l'hypothese de l'embonpoint parental, qui indiquerait que la proliferation automnale a une incidence sur l'embonpoint des adultes en frai et, donc, sur le recrutement. L'absence d'une correlation entre la proliferation automnale et le recrutement dans le stock du golfe du Maine peut etre attribuee a la difference des frequences des proliferations automnales entre les regions des deux stocks. Il semble que l'embonpoint parental et la survie des larves ont tous deux une incidence sur le recrutement d'aiglefins. Toutefois, l'incidence relative de ces effets depend de la nature divergente des facteurs environnementaux de l'ecosysteme. [Traduit par la Redaction], Introduction The lack of explanatory relationships between spawning stock biomass (SSB) and recruitment and the complexity of the underlying processes governing recruitment continues to challenge fisheries managers and scientists (Szuwalski [...]

Drowned terrestrial wetland environments, such as lakes, marshes, and beaches, were thought to be rare in formerly glaciated regions like the Gulf of Maine (United States). In the northwestern Gulf of Maine, postglacial relative sea-level changes include a 'slowstand' between 11.5 ka and 7.5 ka, when the ocean rose doi: 10.1130/G31002.1

Most high-resolution, proxy-based paleoclimate research has concentrated on tropical oceans, while mid- and high-latitude marine regions have received less attention, despite their importance in the global climate system. At present, sclerochronological analyses of bivalve mollusks supply the bulk of annual- to subannual-resolution extratropical marine climate data, even though interpretation is complicated by a slowdown of growth with increasing shell age. Hence, in order to address the need for additional high-resolution proxy climate data from extratropical regions, we conducted the first year-long in situ field calibration of the coralline red alga Clathromorphum compactum in the Gulf of Maine, United States. Coralline red algae are widely distributed in coastal regions worldwide, and individual calcified plants can live continuously for several centuries in temperate and subarctic oceans. Stable oxygen isotopes extracted at subannual resolution from growth increments of monitored specimens of C. compactum relate well to in situ-measured sea-surface temperatures during the May to December calcification period, highlighting the suitability of coralline red algae as an extratropical climate archive. Furthermore, there is a strong correlation between a 30 yr [[delta].sup.18]O record of C. compactum and an instrumental sea-surface temperature record (r = -0.58, p = 0.0008) and a proxy reconstruction derived from the bivalve Arctica islandica collected in the central Gulf of Maine (r = 0.54, p = 0.002). Keywords: coralline red algae, paleoclimate, Clathromorphum, Gulf of Maine, sclerochronology.

Understanding of long-term dynamics of intense coastal storms is important for determining the frequency and impact of these events on sandy coasts. We use optically stimulated luminescence (OSL) dates on relict scarps within a prograded barrier sequence to reconstruct the chronology of large-magnitude erosional events in the western Gulf of Maine. OSL dates obtained on quartz-rich sediments immediately overlying relict scarps indicate severe beach erosion and retreat due to erosional events ca. 1550, 390, 290, and 150 cal yr B.P. Our data provide new evidence of increased storm activity (most likely frequency and/or intensity of extratropical storms) during the past 500 yr, which was preceded by a relatively calm period lasting ~1000 yr. The width of the coastal sequence preserved between successive paleoscarps shows strong correlation with the time interval elapsed between storms. Our findings indicate that diagnostic geophysical and sedimentological signatures of severe erosional events offer new opportunities for assessing the impact and timing of major storms along sandy coasts. Keywords: barrier, ground-penetrating radar, OSL dating, heavy minerals, erosion, Maine.

The plume advection hypothesis links blooms of the toxic dinoflagellate Alexandrium fundyense in the western Gulf of Maine (GOM) to a buoyant plume derived from river outflows. This hypothesis was examined with cruise and moored instrument observations in 1993 when levels of paralytic shellfish poisoning (PSP) toxins were high, and in 1994 when toxicity was low. A coupled physical-biological model simulated hydrography and A. fundyense distributions. Initial A. fundyense populations were restricted to low-salinity nearshore waters near Casco Bay, but also occurred in higher salinity waters along the plume boundary. This suggests two sources of cells--those from shallow-water cyst populations and those transported to shore from offshore blooms in the eastern segment of the Maine coastal current (EMCC). Observations confirm the role of the plume in A. fundyense transport and growth. Downwelling-favorable winds in 1993 transported the plume and its cells rapidly alongshore, enhancing toxicity and propagating PSP to the south. In 1994, sustained upwelling moved the plume offshore, resulting in low toxicity in intertidal shellfish. A. fundyense blooms were likely nutrient limited, leading to low growth rates and moderate cell abundances. These observations and mechanisms were reproduced by coupled physical-biological model simulations. The plume advection hypothesis provides a viable explanation for outbreaks of PSP in the western GOM, but should be refined to include two sources for cells that populate the plume and two major pathways for transport: one within the low-salinity plume and another where A. fundyense cells originating in the EMCC are transported along the outer boundary of the plume front with the western segment of the Maine coastal current.

Ultrasonic, depth-sensitive transmitters were used to track the horizontal and vertical movements, for up to 48 h, of 11 adult (136 to 340 kg estimated body mass) North Atlantic bluefin tuna (Thunnus thynnus Linnaeus). Fish were tracked in October 1995, September and October 1996, and August and September 1997 in the Gulf of Maine, northwestern Atlantic. The objective was to document the behavior of these fish and their schools in order to provide the spatial, temporal, and environmental information required for direct (i.e. fishery-independent) assessment of adult bluefin tuna abundance using aerial surveys. Transmitters were attached to free-swimming fish using a harpoon attachment technique, and all fish remained within the Gulf of Maine while being followed. Most of the bluefin tuna tagged on Stellwagen Bank or in Cape Cod Bay (and followed for at least 30 h) held a predominately easterly course with net horizontal displacements of up to 76 km [d.sup-1]. Mean ([+ or -]SD) swimming depth for all fish was 14 [+ or -]4.7 m and maximum depth for individuals ranged from 22 to 215 m. All but one fish made their deepest excursions, often single descents, at dawn and dusk. In general, adult bluefin tuna spent < 8% of their time at the surface (0 to 1 m), < 19% in the top 4 m, but > 90% in the uppermost 30 m. Mean ([+ or -]SD) speed over ground was 5.9 km [h.sup.-1], but for brief periods surpassed 20 to 31 km [h.sup.-1]. Sea surface temperatures during tracking were 11.5 to 22.0 [degrees] C, and minimum temperatures encountered by the fish ranged from 6.0 to 9.0 [degrees] C. Tagged bluefin tuna and their schools frequented ocean fronts marked by mixed vertebrate feeding assemblages, which included sea birds, baleen whales, basking sharks, and other bluefin schools.

Accumulations of deltaic and littoral sediments on the inner continental shelf of Maine, Gulf of Maine, preserve a record of postglacial sea-level changes and shoreline migrations. The depositional response of coastal environments to a cycle of regression, lowstand, and transgression was examined with seismic-reflection profiles, vibracores, and radiocarbon dates collected from sediments at the mouths of the Kennebec and Penobscot Rivers. Sequence-stratigraphic analysis of these data reveals two distinctly different successions of late Quaternary deposits that represent end members in an evolutionary model for this glaciated coast. Seaward of the Kennebec River, coarse-grained shorelines with foreset beds occur at depths of 21-60 m and outline the lobate margin of the Kennebec River paleodelta, a complex, rock-framed accumulation of glaciomarine and deltaic sediments capped by estuarine and marine deposits. Sand derived from this system today supports large barrier spits and extensive salt marshes. In contrast, the mouth of the Penobscot River is characterized by thick deposits of glaciomarine mud overlain by marine mud of Holocene age, including gas-charged zones that have locally evolved into fields of pockmarks. The distinct lack of sand and gravel seaward of the Penobscot River and its abundance seaward of the Kennebec River probably reflect differences in sediment sources and the physiography of the two watersheds. The contrasting stratigraphic framework of these systems demonstrates the importance of understanding local and regional differences in sediment supply, sea-level change, bedrock structure, and exposure to waves and tides in order to model river-mouth deposition on glaciated coasts. Evolution of shelf deposits was largely controlled by relative sea level, which locally fell from a highstand (+60 to +70 m at 14 ka) contemporary with deglaciation to a lowstand (-55 m at 10.8 ka). The sea-level lowering was accompanied by fluvial incision of older deposits, producing a regressive, basal unconformity. Major rivers deposited abundant sediment over this surface. Sea level then rose at varying rates, extensively reworking formerly emergent parts of the shelf and producing a shoreface ravinement surface in areas exposed to waves. A tidal ravinement surface has developed in sheltered embayments where erosion is due mainly to tidal currents. Incised valleys in both settings preserve transgressive estuarine deposits that contain lagoonal bivalves and salt-marsh foraminifera at depths of 15-30 m. These deposits accumulated ca. 9.2-7.3 ka, locally a period of relatively slow sea-level rise.

New radiocarbon-dated cores obtained by Vibracorers in the western Gulf of Maine confirm that a short-lived, relative sea-level lowstand of [approximately] -55 m occurred at 11-10.5 ka. These cores and younger salt-marsh data also reveal that rates of transgression varied throughout the Holocene, probably due to local variations in glacial isostasy. The isostatic component is resolved by subtracting published approximations of eustatic sea level from our well-determined observations of local relative sea level. A large peak in the isostatic curve coincides with the lowstand and is interpreted as a forebulge 20-25 m in amplitude. Forebulge migration is estimated at 7-11 km/100 yr, based on the timing of lowstands across the region.

Metridium senile, the frilled sea anemone, and Modiolus modiolus, the northern horse mussel, are important members of benthic suspension-feeding assemblages at several rocky hard-bottom subtidal (30-35 m) sites in the Gulf of Maine. Measurements of food availability, rates of food capture, absorption efficiencies, and standard metabolic costs show that inshore populations of Metridium senile have a significantly lower scope for growth than offshore populations, despite higher mean concentrations of particulate organic matter inshore. Similar measurements and calculations for Modiolus modiolus reveal the opposite pattern. These differences persisted at both of these sites during two summers, 1989 and 1990, when differences in mean temperature were not physiologically significant. Thus temperature is precluded as the primary effect on metabolism and growth. We suggest that these physiological differences reflect a response to flow regime and food availability that appears to be manifested differently for Metridium senile and for Modiolus modiolus, a passive and an active suspension feeder, respectively. Results from a reciprocal transplant experiment, to measure growth rates, carried out over a one-year period support the calculated scope for growth during the season when maximum growth rates would be expected. The flux of seston appears to be an important factor affecting the organismal performance of the passive suspension feeder (M. senile), whereas the concentration of seston is more important for the active suspension feeder (M. modiolus)., Introduction Throughout the rocky subtidal region of the Gulf of Maine (GOM), sessile suspension-feeding invertebrates are a dominant feature of benthic communities (Witman and Cooper, 1983; Sebens, 1985; Witman, 1985; [...]

We photographically identified 534 individual fin whales (Balaenoptera physalus) in the Gulf of Maine from 1980 to 1988, including 64 females and 40 young. Arrival patterns of mother-young pairs were similar to other whales within years. Individual females showed strong site fidelity to either the northern or southern Gulf of Maine, suggesting substock separation on the feeding range. Gross annual rates of reproduction (proportion of individuals that were young-of-the-year) for the Gulf of Maine ranged from 0.03 to 0.12 (Arithmetic mean of sample = 0.08) among years. Greater proportions of young were observed in samples from the southern Gulf of Maine (Arithmetic mean of sample = 0.12) than in the northern Gulf of Maine (Arithmetic mean of sample = 0.05). Greater proportions of females also were observed in the southern Gulf of Maine (Arithmetic mean of sample = 0.22 than in the northern Gulf of Maine (Arithmetic mean of sample = 0.10). The average time between consecutive births was 2.71 years, which represented a crude birth rate of 0.37 young per mature female per year. We estimated a potential mean interval of birthing of 2.24 years by making some assumptions for three females with incomplete sighting histories. The overall gross annual rates of reproduction that we observed were similar to rates predicted by harvest data, but rates from the northern Gulf of Maine were less than predicted. Spatial segregation of sexes or age classes may be occurring within the Gulf of Maine.

Every spring, most (and perhaps all) of the right whales known to exist in the North Atlantic - about 300 to 350 individuals - migrate to the shallow Great South [...]