Off the coast of central California, USA, small black rockfish Sebastes melanops (individuals below the length at 50% maturity) comprise a large percentage of the catch in recreational fisheries, yet little is known about the movements of these small fish. To better understand their movements, we implanted acoustic transmitters into 23 black rockfish (29 to 41 cm total length) in Carmel Bay, California, USA. Tagged fish were monitored over a 16 mo period between August 2006 and January 2008. Their vertical movements were correlated with environmental variables such as atmospheric pressure, wind speed, upwelling, and wave height. From October to May, black rockfish moved to deeper waters offshore during the day and returned at night. In the summer, diurnal movements of black rockfish decreased in frequency, perhaps due to locally abundant food resources associated with seasonal upwelling. About two-thirds of the tagged black rockfish (14 fish) displayed a high degree of residency to the study area (>11 mo). The remaining third (9 fish) left the study area within 6 mo of release; signals from 4 of these fish were later detected on other acoustic receiver arrays > 50 km north of Carmel Bay. Storms may have caused those fish to move northward in winter. When in residence, the mean home range of tagged fish was 0.25 km 2 . Our results indicate that a better understanding of the variability of fish movements among age classes is necessary to design marine protected areas (MPAs) that are intended to protect all life stages of a species.
Human access routes to coastal subsistence resources are being altered in Arctic regions as temperatures warm. The accessibility dimension of climate impacts on coastal resources is critical to food sovereignty and resilience of Indigenous Arctic communities, yet the issue of access is understudied relative to food availability. This issue also has implications for the role of governmental agencies in mediating resource access in a changing landscape. We examined the role of climate stressors in affecting access to customary and traditional foods (subsistence) by Indigenous (Iñupiat) communities within and near Arctic National Parklands. We apply access theory to better understand (1) the climate stressors that most impact access to coastal animals and harvest areas, (2) how they affect the availability and reliability of harvest of coastal species, and (3) the mechanisms that facilitate or constrain access to coastal subsistence resources. Our study employed a combination of expert interviews and synthesis of pre-existing environmental time series data in the communities of Kotzebue and Kivalina, Alaska. We found that chronic climate stressors (sea ice retreat, coastal erosion, and changes in weather) most impacted harvest access. To mediate these changes, harvesters ubiquitously reported the use of access mechanisms including capital, knowledge, technology, and social identity; social relations, authority, and time were also reported at high rates. Potential adaptations in these communities include increased reliance on technology and capital to access animals despite landscape changes (e.g., using boats in the absence of sea ice), switching species or relying on social networks for sharing resources when animals become harder to find, and exploring alternatives to harvesting (such as growing food) in response to increasing access challenges. Our findings highlight the stewardship and sovereignty of Indigenous communities as a basis for resilience in a rapidly changing environment.
Olive (Sebastes serranoides), black (Sebastes melanops), and blue rockfish (Sebastes mystinus) are all common inhabitants of nearshore ecosystems on the West coast of North America and important components of the recreational fishery off California. Acoustic monitoring studies indicate that olive rockfish are highly residential and that black rockfish are capable of long migrations and have less site fidelity; yet little is known about the long-term movements of blue rockfish. External tag-recapture studies indicate that blue rockfish may have intermediate movements relative to these congener nearshore species. To better understand the site fidelity, and daily and seasonal movements of blue rockfish over long (>1-year) time scales, we placed acoustic transmitters into 21 adult blue rockfish (30–41 cm total length) in Carmel Bay, California. Blue rockfish displayed intermediate movement patterns and residency relative to other similar kelp forest rockfish species. Two-thirds of tagged blue rockfish (13 fish) exhibited high residency to the study area (>12 mo). When in residence, mean home range of blue rockfish was 0.23 km2, however as many as 30% of tagged blue rockfish shifted their core home range area during the study. Most shifts in home range occurred during upwelling season, and tagged fish moved up to 3.1 km when in residence. Blue rockfish with short residence times were last detected in the study area in late winter and early spring. Blue rockfish were observed at shallower depths during day than night, likely indicative of diurnal feeding. However, over longer time scales, blue rockfish were detected at deeper depths during upwelling periods and with increased wave heights. Daily and seasonal vertical movements of blue rockfish may be influenced by upwelling conditions and local prey abundance.
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