Juvenile largemouth bass Micropterus salmoides, intraperitoneally implanted with microradio transmitters exhibited short‐term (5 days) inflammation around the incision and suture insertion points for both non‐absorbable braided silk and non‐absorbable polypropylene monofilament, but in the longer term (20 days) almost all sutures were shed and the incisions were completely healed. Cumulative mortality was higher for fish with braided silk sutures, however, post‐mortem analysis revealed that violations to the gastro‐intestinal tract from the surgical procedure were the usual cause of the mortality. Mortality was generally low in control fish. The two surgeons who performed the implantations differed substantially in experience. Despite receiving basic training, the novice surgeon took longer to complete the surgeries, had reduced suture precision and experienced more fish mortality relative to the experienced surgeon. For both surgeons, it took longer to complete suturing with polypropylene than with braided silk. During the surgery day, the experienced surgeon exhibited consistently rapid surgery times, whereas the novice surgeon exhibited significantly improved speed as the number of surgeries completed increased. This study suggests that microtransmitters can be successfully implanted in juvenile largemouth bass but some mortality can be expected. This mortality seems to be independent of suture material, but dependent upon the experience of the surgeon.

Zooplankton availability is strongly linked with the growth, survival, and ultimately recruitment of fish during their early life history. We examined how different types of zooplankton affected the growth, survival, and prey selection of larval yellow perch Perca flavescens in a series of laboratory experiments. The growth and survival of newly hatched (5–7‐mm) to 12‐mm yellow perch larvae was greatest when feeding on adult copepods and copepod nauplii. The growth and survival of yellow perch larvae longer than 12 mm was greatest when feeding on adult copepods and small cladocerans. Prey selection patterns closely followed trends in growth and survival; smaller larvae positively selected adult and naupliar copepods, whereas larger larvae selected adult copepods and small cladocerans. Foraging behavior experiments conducted with larvae longer than 12 mm revealed that these fish derived similar energetic gains when feeding solely on adult copepods and small cladocerans. The pathway to this energetic benefit differed substantially between prey types. Adult copepods yielded substantial energy to larval yellow perch because of the minimal handling time involved, despite the lower capture efficiency than with cladocerans. Conversely, yellow perch larvae realized high energetic gain from small cladocerans because of high capture efficiency, despite the higher handling times than with adult copepods. These results illustrate the importance of experimentally quantifying the feeding behavior of fish larvae to gain insight into how larval fish behavior and food type interact to shape larval fish growth patterns.

Climatic variation and dispersal are two primary factors thought to induce recruitment synchrony in fish populations. We hypothesized that climate factors correlated across a broad geographical scale (i.e., the Moran effect) would induce synchrony in recruitment for common carp Cyprinus carpio among 18 glacial lakes across a 175‐km2 area in eastern South Dakota. Cross‐correlation analysis indicated that common carp population fluctuations were highly synchronous among lakes. To evaluate the influence of the Moran effect on recruitment, we examined several candidate models using an information‐theoretic approach. The model with the most support included the interaction of temperature, precipitation, and wind during the open‐water period. This model indicated that the effects of any one of these climate variables on recruitment strength depended on the level of each of the other variables in any given year. Our results suggest that common carp populations in the Midwestern United States exhibit synchronous recruitment across regionwide geographic areas as a result of climatic variability.