The local distribution of basking sharks in the Bay of Fundy (BoF) is unknown despite frequent occurrences in the area from May to November. Defining this species’ spatial habitat use is critical for accurately assessing its Special Concern conservation status in Atlantic Canada. We developed maximum entropy distribution models for the lower BoF and the northeast Gulf of Maine (GoM) to describe spatiotemporal variation in habitat use of basking sharks. Under the Maxent framework, we assessed model responses and distribution shifts in relation to known migratory behavior and local prey dynamics. We used 10 years (2002-2011) of basking shark surface sightings from July-October acquired during boat-based surveys in relation to chlorophyll-a concentration, sea surface temperature, bathymetric features, and distance to seafloor contours to assess habitat suitability. Maximum entropy estimations were selected based on AICc criterion and used to predict habitat utilizing three model-fitting routines as well as converted to binary suitable/non-suitable habitat using the maximum sensitivity and specificity threshold. All models predicted habitat better than random (AUC values >0.796). From July-September, a majority of habitat was in the BoF, in waters >100 m deep, and in the Grand Manan Basin. In October, a majority of the habitat shifted southward into the GoM and to areas >200 m deep. Model responses suggest that suitable habitat from July - October is dependent on a mix of distance to the 0, 100, 150, and 200 m contours but in some models on sea surface temperature (July) and chlorophyll-a (August and September). Our results reveal temporally dynamic habitat use of basking sharks within the BoF and GoM. The relative importance of predictor variables suggests that prey dynamics constrained the species distribution in the BoF. Also, suitable habitat shifted minimally from July-September providing opportunities to conserve the species during peak abundance in the region.

Even with long‐standing management and extensive science support, North American inland fish and fisheries still face many conservation and management challenges. We used a grand challenges approach to identify critical roadblocks that if removed would help solve important problems in the management and long‐term conservation of North American inland fish and fisheries. We identified seven grand challenges within three themes (valuation, governance, and externalities) and 34 research needs and management actions. The major themes identified are to (1) raise awareness of diverse values associated with inland fish and fisheries, (2) govern inland fish and fisheries to satisfy multiple use and conservation objectives, and (3) ensure productive inland fisheries given nonfishing sector externalities. Addressing these grand challenges will help the broader community understand the diverse values of inland fish and fisheries, promote open forums for engagement of diverse stakeholders in fisheries management, and better integrate the inland fish sector into the greater water and land use policy process.

The age and growth of three endemic threatened guitarfish species were analysed using vertebrae of Pseudobatos horkelii, P. percellens and Zapteryx brevirostris. Edge and marginal‐increment analyses were used to evaluate the periodicity of the formation of the band‐pairs, suggesting deposition of one band‐pair per year, from late winter to late spring. The von Bertalanffy growth model was used to describe the growth of these species with the following parameters, for pooled sexes: P. horkelii L∞ = 126.93, k = 0.19 and t0 = −1.51; P. percellens L∞ = 109.31, k = 0.16 and t0 = −1.78; Z. brevirostris L∞ = 60.37, k = 0.24 and t0 = −1.42. Our results are essential to understanding the resilience and vulnerability of these species to harvest, which can contribute to management and conservation actions of these species.

The conservation status of basking sharks Cetorhinus maximus in eastern Canadian waters is not clearly understood, in part because population densities and abundances have not been recently estimated. On September 11, 2009 and 2011, aerial surveys of basking sharks were conducted in the lower Bay of Fundy, Canada. Flyover tests of a wooden shark silhouette revealed that basking sharks were visible to a depth of 5 m. The proportion of time basking sharks were estimated between 0 and 5 m depth (availability bias) was 19% based on 1252 h of time-depth recorder data from 13 free-swimming sharks. During the 2 surveys, 26 sharks were sighted. Using the program Distance, availability bias corrected densities of 0.0513 sharks km −2 (2009, 95% CI = 0.0188 to 0.1402) and 0.0598 sharks km −2 (2011, 95% CI = 0.0358 to 0.1001) were reported. This corresponds to abundance estimates of 542 sharks (2009, 95% CI = 198 to 1482) and 632 sharks (2011, 95% CI = 377 to 1058) occupying a 10 570 km 2 area in the lower Bay of Fundy. Abundance was far lower than previously estimated using indirect methods and untested assumptions (Bay of Fundy = 4200 sharks). Previously published habitat suitability models for basking sharks in the Bay of Fundy predict heterogeneous habitat use, which would lower the overall abundance estimate. This lower population estimate for the Bay of Fundy, coupled with a very limited capacity to respond to significant levels of anthropogenic mortality, raises concerns about the conservation status of eastern Canadian basking sharks.

For many fish species, variation in somatic growth can drive changes in population productivity through the dependence of survival, fecundity, and reproductive schedules on size. Changes in growth arise from many density-dependent and-independent sources. Many assessments of temporal variation in somatic growth rely on methods that lack biological underpinning in the model structure to describe observed relationships between size and environmental conditions. However, biologically-based growth models are needed to examine how density-dependent andindependent factors influence the underlying process of growth (i.e., growth = anabolic factorscatabolic factors). Our objective was to extend biologically-based growth models to estimate temporal variation in somatic growth patterns. A set of hierarchical non-linear mixed effects models based off the von Bertalanffy model and length-weight relationship were developed. We applied the models to a Black Crappie (BC; Pomoxis nigromaculatus) population to assess the impacts of density, chlorophyll A concentration (Chl-a), water level, and temperature on somatic growth. Growth in length was influenced by temperature, with fastest growth at optimal temperatures and slower growth when temperatures were coldest (48% slower) or hottest (82% slower), and was negatively related to density, with 25% slower growth at high density. Weight of age-0 BC was negatively related to chlorophyll A, individuals were 18% lighter at high Chl-a, and positively to temperature, individuals were 10% lighter when water was cooler. Finally, growth in weight of age-1+ BC was negatively related to all factors, with 5-11% lighter fish at high densities, Chl-a, water levels, and temperatures. The model structure developed in this manuscript has broad applicability to populations that have time series data of size-at-age observations, growth increments, or back-calculated sizes and adequate environmental data.

The chronic reliability of bioelectronic neural interfaces has been challenged by foreign body reactions (FBRs) resulting in fibrotic encapsulation and poor integration with neural tissue. Engineered microtopographies could alleviate these challenges by manipulating cellular responses to the implanted device. Parallel microchannels have been shown to modulate neuronal cell alignment and axonal growth, and Sharklet™ microtopographies of targeted feature sizes can modulate bio-adhesion of an array of bacteria, marine organisms, and epithelial cells due to their unique geometry. We hypothesized that a Sharklet™ micropattern could be identified that inhibited fibroblasts partially responsible for FBR while promoting Schwann cell proliferation and alignment. in vitro cell assays were used to screen the effect of Sharklet™ and channel micropatterns of varying dimensions from 2 to 20 μm on fibroblast and Schwann cell metrics (e.g., morphology/alignment, nuclei count, metabolic activity), and a hierarchical analysis of variance was used to compare treatments. In general, Schwann cells were found to be more metabolically active and aligned than fibroblasts when compared between the same pattern. 20 μm wide channels spaced 2 μm apart were found to promote Schwann cell attachment and alignment while simultaneously inhibiting fibroblasts and warrant further in vivo study on neural interface devices. No statistically significant trends between cellular responses and geometrical parameters were identified because mammalian cells can change their morphology dependent on their environment in a manner dissimilar to bacteria. Our results showed although surface patterning is a strong physical tool for modulating cell behavior, responses to micropatterns are highly dependent on the cell type.

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The distribution, abundance, and habitat of cryptic cetacean species such as beaked whales and dwarf/pygmy sperm whales (Kogia spp.) are challenging to study due to their long dive times and/or very limited surface behavior. Even less is known in minimally studied and remote regions, including the Mariana Archipelago and parts of the broader western Pacific. In 2018, we deployed a network of eight Drifting Acoustic Spar Buoy Recorders (DASBRs) on the west side of the Mariana Archipelago with the goal of examining the distribution and habitat of beaked whales and Kogia spp. in this region using passive acoustic monitoring. Concurrently, conductivity-temperature-depth (CTD) data were collected within the drift area and combined with satellite oceanographic data to build Ensemble Random Forest Models to identify specific oceanographic features that determine the distribution of these species. DASBRs deployed at locations ranging from 13°N to 18°N generally drifted from east to west between the Mariana Archipelago and the West Mariana Ridge. Spectral and temporal characteristics of echolocation signals were used to identify the presence of beaked whales and Kogia spp. species. This dataset contained frequency modulated (FM) pulses characteristic of Longman’s (Indopacetus pacificus), Cuvier’s (Ziphius cavirostris), and Blainville’s (Mesoplodon densirostris) beaked whales, as well as the unidentified beaked whale FM pulse known as the “BWC,” along with narrow-band high frequency clicks from Kogia spp. The detection rate was substantially higher for all species on the five tracks in the region north of 15.5°N than for those drifts occurring farther south. Species distribution models suggest that differences in the oceanographic characteristics between the northern and southern regions may impact foraging opportunities, possibly explaining the specific ecological niche for these species within this water mass. This is the first study of the distribution of cryptic cetacean species within the wider Mariana Archipelago region. We demonstrate that autonomous drifting acoustic recorders, combined with environmental sampling and remote satellite data are a powerful tool for studying the habitat dependent distribution of cryptic cetacean species.