Pelagic forage fishes play critical roles in productive marine food webs by providing a link between zooplankton and piscivores and transferring energy from feeding grounds to other ecosystems. The amount of energy moved to higher trophic levels or new systems is directly linked to the consumption rate of pelagic forage fishes. In the Gulf of Maine, Atlantic herring (Clupea harengus) is the dominant forage fish; the purpose of this study is to determine their specific consumption rate (g prey/g fish/day). Using fish collected in autumn 2012 and spring 2013, we applied a mercury mass-balance model to estimate individual and population consumption of Atlantic herring in the Gulf of Maine. Our results suggest that the specific consumption rate increases from age 1.5 until age 6 (years) and then asymptotes. These estimates were contradictory to much of what exists in the literature; for most fishes, specific consumption estimates decrease with age and overall are much lower than our estimates. We looked further into our results to explore the underlying cause of the increase in specific consumption rate. We combined the mercury mass-balance model with a Wisconsin (WI) bioenergetics model and ran several simulations adjusting the most sensitive factors in each--prey mercury in the former and activity in the latter. The results of our simulations showed that an increase in activity relative to age and mass can best explain the increase in the consumption rate of Adult herring. This suggests that an ontogenetic shift to migration in adult Atlantic herring results in increased energy demand with age, and ultimately increased consumption.

Thesis advisor: John E. Ebel / Large magnitude offshore passive margin earthquakes are rare, making small magnitude events (M < 4) the predominant data available to study the mechanisms of seismicity along passive margins. This study is focused on a swarm of events (M2.1-M3.9) that occurred from 2012-2013 located in the Gulf of Maine (GM) along the Atlantic Passive Margin (APM) shelf break, a region with previously minimal recorded seismic activity. Relative locations were calculated for the earthquakes of the GM swarm and a moment tensor inversion method was used to calculate focal mechanisms for the two largest events in the swarm. The results of the relative location method constrained a fault orientation to a strike of 243° ± 3° and a dip of 25° ± 3°. The focal mechanisms for the two largest events were determined to be oblique normal faults with steeply dipping planes at depths between 12-18 km. For the largest event (M3.9), the strike is 235° ± 1°, with a dip of 77.7° ± .8° and a rake of -116.5° ± 3°, and for the second largest event (M3.7) the strike is 259° ± 3°, with a dip of 78° ± 2° and a rake of -58.8° ± 7°. By mapping the spatial extent of the relative hypocenters, I infer a potential fault size of 2.7 km by 2.4 km. If this entire area were to rupture at once in the future, an earthquake of M4.9-M5.0 could occur, a magnitude not large enough to be tsunamigenic in the GM. Based on Gutenberg-Richter relations from the eastern APM, if a M7 can occur in the GM, its estimated mean repeat time is 2,120-22,800 years, and it could be tsunamigenic depending on the event’s proximity to the continental slope. / Thesis (MS) — Boston College, 2016. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.

Following catastrophic exploitation throughout the North Atlantic, breeding seabird populations have begun to recover thanks to regulatory protection and restoration and management efforts. As bird populations increase, new challenges emerge, including overgrowth of vegetation that limits the open nesting habitat favored by most tern species. Though managers have used a variety of measures to reduce vegetation cover, these techniques have rarely been quantified or compared experimentally. During the summers of 2009 and 2010, I applied two different techniques, controlled burning and artificial weed barriers (muslin fabric and artificial turf) to experimental plots on Eastern Egg Rock and Outer Green Island, near-shore seabird nesting islands in mid-coastal Maine. I then monitored vegetation regrowth and use by nesting terns to assess the effectiveness of these techniques for opening and maintaining Common Tern nesting habitat during a full breeding season, comparing treated plots to vegetated control plots and existing tern nesting habitat. Burned areas did not remain open for the full nesting season, but regrew shortly after laying, leading to near-complete nest failure in these plots. Tern nest and fledging success was similar in weed barrier (1.37 chicks/pair) and untreated tern nesting habitat (1.38 chicks/pair) plots. Replacement of existing vegetation, tested at a limited scale on Outer Green Island, did not succeed. These three techniques represent only a small fraction of vegetation management techniques used throughout the North Atlantic region. Through literature review and consultation with North Atlantic colony managers, I collected information on vegetation management on 34 tern nesting islands between 33 and 55° N latitude and developed a summary of different vegetation control techniques used. I identified 14 technique types suitable for use in nesting colonies: i.e., that can be applied before and after (but not during) the nesting period of May-July, that do not cause destructive impacts to the surrounding ecosystem, and that involve materials and labor that can be transported to inaccessible offshore islands. Of these techniques, 8 created usable tern nesting habitat for a full breeding season, and the most successful techniques required constructing habitat over existing vegetation. The success of different methods depended heavily on the plant communities and soil types involved. In general, vegetation management options were more limited and less successful for elevated, rocky islands than for low, sandy islands. Often, techniques that successfully removed one species or group of species (i.e., perennial grasses) failed due to rapid colonization by other species (i.e., herbaceous annuals). This review of past and ongoing vegetation management techniques used on seabird nesting islands, including their costs, methods for application, and effectiveness, provides seabird managers a reference when evaluating current and future vegetation management programs.

A new macroscopic ovarian reproductive maturity index for haddock, Melanogrammus aeglefinus L, was developed to improve field collection of reproductive stage data. The index was tested, validated and revised based on a comparison with a laboratory histological staging method. The comparison of field and histological observations helped to improve the field index and methodologies and provided useful insight into the reproductive biology of Haddock. Although laboratory staging based on histology is inherently more accurate than any macroscopic field staging method, field observations can reveal weaknesses in the laboratory approach due to sampling bias. The revised field index includes three new macroscopic stages that represent a progression in final oocyte maturation from early to late, which were found to be reliable for staging spawning readiness in the field. This index was then used to study a population of Haddock in the Gulf of Maine to determine if it exhibits diel spawning periodicity. Commercial fishing vessels were chartered for 25 dedicated longlining trips to collect sexually mature haddock in the Southwestern Gulf of Maine at locations identified by commercial fishers as having spawning aggregations. In order to examine diel effects on haddock reproduction, the change in catch per unit effort and percentage of male and female haddock of all reproductive maturity stages together with the gonadosomatic index were observed across a 24 hour diel cycle. Only females in hydration stage 3 (defined as late final oocyte maturation stage ovaries with 50-75% of oocytes hydrated) were significantly affected by time of day with significant increases in both catch per unit effort and percentage of hydration stage 3 haddock during the night. Because H3 is the most advanced reproductive stage observed prior to a spawning event and therefore the best indicator of imminent spawning these results demonstrate that female haddock in Southwestern Gulf of Maine primarily spawn during night hours with a peak between 2100 and 0100 hours. No diel trend was observed for any male reproductive stages. Additionally, no diel trend was observed in male or female reproductive stages unrelated to spawning including immature, spent and resting.

The Gulf of Maine is a dynamic ecosystem with rapidly warming sea surface temperatures (SSTs), therefore it is vital to understand how species interactions vary over time and space. In chapter two, I quantify and compare dietary differences among four tern species, across seven islands in the region, over a 32-year period. Multivariate statistical analyses were employed to discern spatial and temporal differences in foraging ecology. Findings suggest there are significant differences between species and islands; however, only three prey species comprise the majority of chick diet for all terns and islands. The reliance on only a few prey items led to narrow foraging niches, potentially increasing their vulnerability to climate change, fisheries practices, or other localized disturbances. The third chapter characterizes long-term trends across nesting islands, describes within-season dietary phenology, and quantifies how warming SSTs may influence diet. Over time there was a declining trend in the occurrence of hake and increasing amounts of sand lance. In addition, hake and sand lance occur with higher frequency earlier in the season, while butterfish and “other fish” showed the opposite trend. Furthermore, results indicated that the within-season decline of hake occurs more rapidly in years with earlier spring thermal transition dates potentially indicating a phenological shift. Finally, warming SSTs were found to be negatively correlated with hake and positively correlated with the “other fish” prey group. Given projections of further warming in the region, understanding how the diet of these seabirds may be impacted in crucial to their conservation.

During 2008 – 2009, we quantified foraging behavior of adult Atlantic puffins (Fratercula arctica) by deploying time-depth recorders (TDRs) on 18 adults and collected morphological measurements from 40 adults nesting on Petit Manan Island, Maine. Dive data were successfully retrieved from 5 birds foraging for 14 days in 2008, and 8 birds foraging for 18 days in 2009. Pooling across all birds, a total of 8,097 dives were recorded, with peaks in activity during 0400-0800 and 1600-2000, and no diving between 2100 and 0400. Mean (± SD) dives/bird/day was 276.4 (± 84.7), with dives grouped into bouts lasting 17.8 (± 31.5) minutes, consisting of 8.9 (± 3.4) dives. Dive depth was less than 15 m for 86% of the dives. Mean maximum dive depth across birds was 9.7 (± 1.7) m, with the deepest dive being 40.7 m. Females made fewer deep dives (27-41 m), had more midday dives (1000 - 1559), and their dives were spread across a greater number of bouts per day than males. Given a mean foraging trip length of 60.1 (± 38.3) minutes for 26 birds observed in 2009, we estimate that adult puffins foraged, on average, within 31 km of the colony. Morphological measures were recorded by a single observer and included body mass, wing chord, bill depth, bill length, culmen, and head-bill length, and represented 19 males and 21 females, based on blood sample analysis. Data were analyzed using classification trees, and our final tree used culmen length and bill depth to correctly classify 34 of 40 (85%) birds (kappa = 0.695, P < 0.01). Use of our model can greatly improve the ability of biologists to identify sex of puffins in the field at this colony site, but variability in morphological data we collected at addition colonies indicates that future work is needed to determine its applicability throughout the Gulf of Maine. During 2009, we measured burrow characteristics of alcids and empty burrows. Breeding success and burrow characteristics were measured for nests of 104 puffins, 58 guillemots and 4 razorbills, with burrow characteristics measured for an additional 12 guillemot and 56 empty burrows. Mean diameter of burrow openings of puffins, guillemots, razorbills and empty burrows were significantly different, and artificial puffin burrows had significantly smaller openings than natural while artificial and natural guillemot burrows had similar opening diameters. Hatch, chick, and nest success of puffins was similar among burrow types, but guillemots had higher hatch and nest success in artificial burrows. The variables we used to create models for predicting hatch and nest success for puffins and guillemots had inadequate discriminatory power to predict success.

No description available.

Population structure and vital rates of Gulf of Maine (GOM) humpback whales, Megaptera novaeangliae, were studied by a combination of longitudinal data, region-wide surveys and modern mark-recapture statistical methods. Demography and rates of exchange were examined among six GOM areas. Juveniles and females were preferentially encountered in southern GOM habitats, including at the Studds Stellwagen Bank National Marine Sanctuary (SBNMS). Multi-state modelling also revealed unequal probabilities of movement between areas that was not explained by inter-area distance, adjacency, whale density or dominant prey type. Aerial surveys and photo-identification data indicated that the population was likely closed to migration between June and September. Otherwise, seasonal trends in population composition were consistent the demographically staggered migration reported in other oceans. Over-wintering occurred,but there was little evidence that a significant number of humpback whales failed to undertake or complete migration each year. Vital rates varied with sex, age and time. Juveniles exhibited lower and more variable survival than adults and so were a potential source of downward bias in “non-calf” survival estimates. Males exhibited higher survival than females and achieved maximal survival at age five, the estimated age at male puberty. By contrast, females did not reach peak survival until the current average age at first birth (8.78 years, s = 2.33). The latter was significantly higher than previous estimates and females that recruited by age seven had a lower likelihood of subsequent survival than those that recruited late. Costs of reproduction persisted into adulthood, with breeders exhibiting lower survival than nonbreeders. Calves born during years of low fecundity exhibited lower survival than those born when fecundity was high, possibly due to lower maternal investment. Costs of reproduction have not previously been described in cetaceans, but are consistent with the risks potentially associated with capital breeding.

New England’s seafood industry has been searching for opportunities to diversify their landings and build resilience as it faces socio-economic challenges from a changing climate. Developing markets for underutilized species is one way the New England community could help their seafood industry build resilience. This thesis identified New England’s underutilized fish species and explored their marketplace potential by examining their availability in a changing climate, current availability to consumers, and consumers’ responses. In Chapter I, I account how New England’s seafood preferences have changed over time. In Chapter II, I identify New England’s seven underutilized seafood species: 1) Acadian redfish (Sebastes fasciatus), 2) Atlantic pollock (Pollachius virens), 3) butterfish (Peprilus triacanthus), 4) the Georges Bank and Georges Bank East stocks of haddock (Melanogrammus aeglefinus), 5) scup (Stenotomus chrysops 6) the northern stock of silver hake (Mercluccius bilinearis), and 7) white hake (Urophycis tenuis). In the same chapter, I show that climate change will likely affect the availability of these species differently and that the broader ecological and socio-economic responses from shifting distributions and phenology are largely unknown. In Chapter III, I demonstrate that besides haddock, underutilized species were rarely accessible to consumers in restaurants. In the same chapter, I show how resources would likely help consumers and restaurants connect with their underutilized species since popular seafood suggestion guides either overlook or provide inconsistent recommendations for all underutilized species. In Chapter IV, I suggest that younger generations (Millennials and Generation Z) are interested in engaging with underutilized species. These younger consumers responded positively to hake, haddock, and Atlantic pollock in sensory assessments. Finally, in Chapter V, I suggest how New England’s seafood supply chain can use results from this research to make more informed policy, marketing, and purchasing decisions that align with their sustainability goals. These insights into availability, access, and consumer response may help New England’s seafood industry strategize approaches that will connect younger consumers to their local seafood options and build new adaptive markets in a changing climate.

During the summers of 2007-2009, I studied the population growth and reproductive and foraging ecology of the Razorbill (Alca torda) at Matinicus Rock (MR), Maine. This medium-sized marine bird in the family Alcidae (auks) was extirpated from the Gulf of Maine in the late 19th century by hunting, collecting, and colony disturbance. Following legislation protecting seabirds and their nesting habitats, the Razorbill has recolonized probable former nesting habitat in the Gulf of Maine during the past several decades. Six small colonies comprise the Maine population, which is listed as threatened and forms the southern extension of the species breeding distribution. In Chapter 1, I present a population model of the MR breeding colony, based on studies of population growth and reproductive success, and supplemented with previously collected data from the National Audubon Society Seabird Restoration Program (Project Puffin), with whom I collaborated. I also describe chick diet (supplemented with Project Puffin data) and draw connections between diet and reproductive success. I found that reproductive success was too low to account for the observed population growth rate, and conclude that the colony is a sink population supported by substantial immigration. Because annual fledging success was positively associated with prey quality, I suggest that substandard chick diet may contribute to the sink population dynamic via diet-driven depressed fledging success. In Chapter 2, I report on the foraging behavior of chick-rearing Razorbills fitted with bird-borne data-loggers at MR in 2008-2009. I describe diving behavior including depth, duration, and profile shape of dives, as well as diel patterns. Diving activity was restricted to daylight hours, and dives were shallowest and most frequent in the evening. Though generally similar to diving behavior reported at four European and Canadian colonies, Razorbills at MR performed three times as many dives per day as at the Gannet Islands, Labrador, and the mean dive depth was greater than three of four previous studies. Deeper and more frequent dives may indicate higher foraging effort and lower prey availability. Reproductive success would suffer if parents cannot buffer chicks against the effects of low prey availability through increased foraging effort or other behavioral modifications. Together, the pieces of our research indicate that prey availability may be negatively affecting reproduction and population growth at MR. Rapid colony growth cannot be explained by local reproductive success, and is likely the result of substantial immigration from other colonies. Chick diet is varied and includes multiple high-quality forage fish species, yet chicks also consume poor-quality prey (larval fish and euphausiids) that may signal periods of very poor prey availability. Frequency and depth of dives made by chick-provisioning adults are also suggestive of parents allocating extra effort to foraging, relative to other colonies.