We studied the effects of catch-and-release angling on rock bass Ambloplites rupestris, a small but common centrarchid species in North America. A field study of hooking injury and mortality was conducted in Lake Erie at a water temperature of 16ЊC. We captured fish using one of four terminal tackle types: barbless worm, barbed worm, barbless jig, and barbed jig. No mortality was observed in any of the four treatments even after holding fish for 5 d. Fish captured using worms were hooked more deeply than fish caught on jigs. Fish captured on barbless jigs were unhooked most easily and more rapidly than with all other tackle types, resulting in an average of only 20 s of air exposure. Because they were more difficult to remove from the hook, fish captured on other terminal tackle experienced at least twice as much air exposure. To assess sublethal effects, we measured the cardiac responses of rock bass exposed to 30 s of simulated angling followed by 30 or 180 s of air exposure. These air exposure durations were intended to simulate the conditions faced by fish that were either easy or difficult to remove from the hook. Fish experienced arrhythmia during angling, although overall cardiac output increased. Fish experienced severe bradycardia during air exposure, but after being returned to the water, all fish exhibited elevated cardiac output. Fish exposed to 30 s of air exposure required 2 h for full recovery, whereas those exposed to 180 s of air required 4 h. During periods of cardiac disturbance, increases in cardiac output were due to both heightened heart rate and stroke volume. Our results suggest that hooking mortality did not vary with bait or hook type and that physiological disturbance of rock bass was influenced by the duration of air exposure, as influenced by bait and hook choice. We recommend that anglers attempt to minimize handling and air exposure of angled fish and keep pliers or other hook removal devices readily accessible to facilitate rapid release of fish not intended for harvest.

We examined the assumption that landscape heterogeneity similarly influences the spatial distribution of genetic diversity in closely related and geographically overlapping species. Accordingly, we evaluated the influence of watershed affiliation and nine habitat variables from four categories (spatial isolation, habitat size, climate, and ecology) on population divergence in three species of Pacific salmon (Oncorhynchus tshawytscha, O. kisutch, and O. keta) from three contiguous watersheds in subarctic North America. By incorporating spatial data we found that the three watersheds did not form the first level of hierarchical population structure as predicted. Instead, each species exhibited a broadly similar spatial pattern: a single coastal group with populations from all watersheds and one or more inland groups primarily in the largest watershed. These results imply that the spatial scale of conservation should extend across watersheds rather than at the watershed level which is the scale for fishery management. Three independent methods of multivariate analysis identified two variables as having influence on population divergence across all watersheds: precipitation in all species and subbasin area (SBA) in Chinook. Although we found general broad-scale congruence in the spatial patterns of population divergence and evidence that precipitation may influence population divergence in each species, we also found differences in the level of population divergence (coho [ Chinook and chum) and evidence that SBA may influence population divergence only in Chinook. These differences among species support a species-specific approach to evaluating and planning for the influence of broad-scale impacts such as climate change.

Although regulations prohibiting the use of natural baits are relatively common, new regulations specifically targeting the use of chemical attractants have recently been implemented. While no citeable evidence for these new regulations exists, they may have been promulgated due to a perceived increase in the risk of fish mortality from scented lures compared with unscented lures. The present study investigated the hooking injury and short‐term mortality of 238 adult smallmouth bass Micropterus dolomieu captured on Lake Erie by both experienced (fished > 100 d/year) and novice (fished < 10 d/year) anglers on actively fished jigs similarly threaded with minnows, nonscented plastic grubs, or grubs scented with chemical attractants. The depth of hook ingestion, the anatomical hooking location, the presence of bleeding at the hook wound, and the total amount of time taken to remove the hook were noted on all captured fish. The fish were then transferred to a retention cage, and their survival was monitored for 72 h before release. None of the fish captured suffered any immediate (<1 h) or short‐term (<72 h) mortality. The type of bait used to capture the fish had no significant effect on the depth of hook penetration or the anatomical hooking location. More experienced anglers, however, hooked the fish significantly deeper in the mouth than the novice anglers. These results suggest that the use of the chemical attractants tested in the present study do not deleteriously affect the injury rates or survival of captured smallmouth bass. Therefore, regulations prohibiting the use of chemical attractants on actively fished single‐hook jigs for smallmouth bass appear unjustified if the intent was to reduce hooking injury and mortality.

No abstract

We used 20 microsatellite loci to compare genetic diversity and patterns of isolation-by-distance among three groups of chum salmon ( Oncorhynchus keta ) from two physically distinct watersheds in western Alaska, USA. The results were consistent with the hypothesis that gene flow decreases as the complexity of the hydrographic system increases. Specifically, higher gene flow was inferred among 11 populations from a nonhierarchical collection of short coastal rivers in Norton Sound compared with 29 populations from a complex hierarchical network of inland tributaries of the Yukon River. Within the Yukon River, inferred gene flow was highest among 15 summer-run populations that spawn in the lower drainage, compared with 14 fall-run populations that spawn in the upper drainage. The results suggest that the complexity of the hydrographic system may influence population connectivity and hence the level of genetic diversity of western Alaska chum salmon. Finally, evidence of isolation-by-time, when controlling for geographic distance, supported the hypothesis that genetic divergence in Yukon River chum salmon is influenced by seasonal run timing. However, evidence of isolation-by-distance, when controlling for season run timing, indicated the populations are not sufficiently isolated, spatially or temporally, to prevent gene flow. Dispersal among summer- and fall-run populations may play a role in maintaining genetic diversity.