Peter S. Rand

Effects of River Discharge, Temperature, and Future Climates on Energetics and Mortality of Adult Migrating Fraser River Sockeye Salmon

Abstract We evaluated the effects of past and future trends in temperature and discharge in the Fraser River on the migratory performance of the early Stuart population of sockeye salmon Oncorhynchus nerka. Fish of lower condition exhibited disproportionately higher mortality during the spawning run, elucidating a critical link between energetic condition and a fishs ability to reach the spawning grounds. We simulated spawning migrations by accounting for energetic demands for an average individual in the population from the time of entry into the Fraser River estuary to arrival on the spawning grounds (about 1,200 km upstream) and estimated energy expenditures for the average migrant during 1950–2001. The model output indicates relatively high interannual variability in migration energy use and a marked increase in energy demands in recent years related to unusually high discharges (e.g., 1997) and warmer than average water temperature (e.g., 1998). We examined how global climate change might effect dis...

Ecological interactions between wild and hatchery salmonids and key recommendations for research and management actions in selected regions of the North Pacific

Advances in salmon culture practices during the latter part of the 20th century provided the opportunity for mass production of juvenile salmon. Hatchery-produced salmon currently outnumber wild salmon in some regions around the Pacific Rim, raising concerns about their ecological impacts on wild salmon. We convened five regional sessions at an international conference to identify and discuss issues related to ecological interactions between wild and hatchery salmon. Session participants were charged with identifying key interaction types by salmon life stage. Each group was asked to summarize key research needs and identify management actions that might be needed to reduce risks from hatchery programs. Some common themes emerged in all the sessions, including the importance of predation and competition interactions in freshwater environments during juvenile life stages and breeding interactions among adults. Much less is understood about interactions in estuarine and marine ecosystems, even though these environments may be critical in determining recruitment success. Some groups identified a need for field experiments to test hypotheses related to ecological interactions and the need to understand and, where possible, control hatchery straying. Some groups also discussed the importance of carrying capacity in different environments and how hatchery programs may be contributing to density-dependent effects. There is a lack of focused studies on ecological interactions between wild and hatchery salmon in the Western Pacific. The authors of this paper hope to encourage new research efforts to better understand ecological interactions to help inform management efforts aimed at reducing hatchery risks to wild salmon.

Ecological interactions between wild and hatchery salmonids: an introduction to the special issue

The optimism of early salmon hatchery practitioners toincrease abundance (Lichatowich 1999) has been tem-pered in recent decades by theoretical and empiricalstudiesindicatingunintendednegativeeffectshatcheriescanhaveonwildPacificsalmonandsteelhead(Naishetal. 2008; Pearsons and Temple 2010). Unintendedeffects of hatcheries are much more difficult and costlyto assess than evaluating the benefits of hatchery pro-duction to provide harvest opportunities. Holisticallyevaluating the relative costs and benefits of past andcurrent hatchery practices requires an understanding andestimation of the unintended effects (Pearsons 2010). Inrecent years, national and local governments, indigenous(e.g. First Nations or tribal) resource agencies, privateindustry and NGO conservation groups have begunefforts to reform public salmon and steelhead hatcherysystems in North America, which include critically eval-uating societal and biological risks and benefits.A significant number of national and internationalpolicy concernsandactions aredirectlyrelevantto thisissue. In the US Pacific Northwest, for example, theNational Oceanic and Atmospheric Administration(NOAA) is currently evaluating the environmentalimpact of salmon and steelhead hatcheries throughfederal mandates such as the Endangered Species Actand the Mitchell Act. The US State of Alaska is facedwith ongoing challenges of adhering to the State’sfisheries policies regarding sustainability, geneticsand escapement goals in the face of a growing privatesalmon hatchery industry in the State. In Canada, theDepartment of Fisheries and Oceans (DFO) is in theprocessofimplementinganambitiousnewWildSalmonPolicythatmustaddressimpactshatcherieshaveonwildsalmon. There is fresh thinking and emerging newinitiativesinbothJapanandRussiatoidentifyandseparately manage wild salmon in these nations.The growing demand for sustainable seafood hasput the global spotlight on salmon, which is near thetop of the list of most desired seafood, buoyed byreports of health benefits of eating salmon. Third partysustainability certifications of wild capture fisheries isrequired in many global markets, and Pacific salmon

Reconstructing Sakhalin Taimen Parahucho perryi Historical Distribution and Identifying Causes for Local Extinctions

Abstract The Sakhalin taimen Parahucho perryi is an endangered salmonid with a natural range limited to the Russian Far East and Japan. We constructed a classification tree to determine the environmental factors shaping the historical global distribution of this species and then predicted its potential geographic range. The distribution was most strongly influenced by a spatial autocorrelation term, indicating that it is highly contiguous. Large drainage basins with low topographic relief and large floodplains had a higher probability of taimen occurrence. The boundary of the global distribution was delineated by mean monthly precipitation within the range of 54–96 mm. The presence of Sakhalin taimen was predicted in many drainage basins where it has never been recorded. We also modeled the status of 48 taimen populations in Japan, where it was possible to classify them into three categories: currently stable (7), endangered (5), and extinct (36). The most significant factor differentiating the 12 extant ...

Sampling and Statistical Considerations for Hydroacoustic Surveys Used in Estimating Abundance of Forage Fishes in Reservoirs

Abstract An understanding of the spatial distribution of forage fish resources is required to make informed fishery management decisions. We used mobile hydroacoustics to assess the distribution and abundance of forage fish in Badin Lake, a reservoir in central North Carolina. By sampling a series of cross-channel and longitudinal transects and analyzing the data using geostatistics, we characterized both large- and small-scale spatial patterns in forage fish density. Forage fish were observed in higher densities in upstream regions of the reservoir and were seen only in surface waters during July 2000 owing to the existence of a strong thermo–oxycline and in two layers (surface and near bottom) during mixed conditions in December 2001. We observed differences in the scale of patchiness (200–700 m) in forage fish distribution depending on the region of the reservoir where sampling took place, and we infer that these patterns are governed by prevailing limnological conditions. Modeling the spatial variatio...

Migration of Sakhalin taimen (Parahucho perryi): Evidence of freshwater resident life history types

Sakhalin taimen (Parahucho perryi) range from the Russian Far East mainland along the Sea of Japan coast, and Sakhalin, Kuril, and Hokkaido Islands and are considered to primarily be an anadromous species. We used otolith strontium-to-calcium ratios (Sr/Ca) to determine the chronology of migration between freshwater and saltwater and identify migratory contingents of taimen collected from the Koppi River, Russia. In addition, we examined taimen from the Sarufutsu River, Japan and Tumnin River, Russia that were captured in marine waters. Transects of otolith Sr/Ca for the Sarufutsu River fish were consistent with patterns observed in anadromous salmonids. Two fish from the Tumnin River appeared to be recent migrants to saltwater and one fish was characterized by an otolith Sr/Ca transect consistent with marine migration. Using these transects as benchmarks, all Koppi River taimen were classified as freshwater residents. These findings suggest more work is needed to assess life history variability among locations and the role of freshwater productivity in controlling migratory behavior in taimen.

Eco-geographic units, population hierarchy, and a two-level conservation strategy with reference to a critically endangered salmonid, Sakhalin taimen Parahucho perryi

Hierarchical population structure can result from range-wide geographic subdivision under conditions of environmental heterogeneity and weak gene flow. While a lower level of structure can be formed by local populations within eco-geographic regions, an upper level can be characterized by variation between populations from different regions, and thus, be represented by evolutionarily significant units (ESUs) defined by environmental, ecological and genetic variation. Selection of ESUs may depend on the sequence of using these three sources of variation. We propose to determine ESUs by first using non-genetic, ecological and geographical gradients for defining preliminary population groups (eco-geographic units, EGUs) and then testing whether the boundaries of these units are genetically coherent and thus represent ESUs or warrant their further modification. We evaluate this approach using Sakhalin taimen, an East Asian endangered endemic fish. Forty-one samples (473 fish) were drawn from thirty populations across the species range and genotyped at microsatellite DNA markers. We assign the populations into ESUs based on geographic and life history criteria and subsequent application of genetic diversity analyses. The ESUs appeared to be greatly diverged genetically. Within ESUs, local populations are genetically differentiated, have low effective sizes, show signatures of demographic decline and extremely restricted gene flow. Conservation plans aimed to restore or maintain a specific threatened population should take into account such hierarchical structure, and in particular be based on the genetic resources drawn from each population or using ecologically and genetically similar populations from the same ESU as donors for restoration of the population.