Development of an Argopecten-Specific 18S rRNA Targeted Genetic Probe

Comparison of 18S ribosomal RNA gene sequences between diverse bivalve species, including eight scallop species, allowed the design of an 18S rRNA targeted oligonucleotide probe (BS-1364) that was specific for scallops belonging to the genus Argopecten (bay and calico scallops). The high sequence similarity of the 18S rRNA gene between Argopecten irradians and Argopecten gibbus (98.8%) prevented the design of an A. irradians species-specific probe. Hybridization studies using amplified 18S rDNA from a diverse collection of bivalve species demonstrated that the specificity of the digoxygenin-labeled probe was consistent with the predicted specificity indicated by sequence comparison. Hybridization studies using laboratory-spawned bay scallop veligers indicated that a single veliger could be detected by probe hybridization in a blot format, and that probe hybridization signal was proportional (r ²= .99) to the abundance of veligers. Methods for rRNA extraction and blotting were developed that allowed bay scallop veligers to be specifically and quantitatively identified in natural plankton samples. Preliminary studies conducted in Tampa Bay, Florida, suggest that introduced scallops can successfully spawn and produce veligers under in situ conditions. The Argopecten-specific probe and methods developed in this study provide the means to study the production and fate of bay scallop larvae in nature and provide evidence that scallops introduced into Tampa Bay have the potential for successful reproduction and enhancement of scallop stocks. Received January 25, 1999; accepted May 7, 1999.     

Donald Richard Nelson: The Most Unforgettable Character I Ever Met

This volume is dedicated to the work, life and memory of Donald Richard Nelson. The present article is based primarily on the author's 38-year friendship and personal experience with the man. The text chronicles his life and times from budding naturalist to champion spearfisher through graduate school and on to becoming scientist, teacher and mentor to dozens of graduate students. The author perceives Nelson as a unique character, creative, introspective, kind, wise and gentle. His influence in the field of contemporary elasmobranch biology, especially ethology and sensory physiology was enormous.     

1株水产饵料用光合细菌粪红假单胞菌的分离筛选

从凡纳滨对虾池塘水样、底泥中分离光合细菌,依次通过菌株培养液性状、菌体粗蛋白含量、类胡萝卜素、氨基酸及辅酶Q种类和含量综合评价,筛选营养成分较丰富的菌株,为鱼虾贝类提供优良的开口饵料。试验共分离得到35株光合细菌,其中11株菌液均一、稳定且颜色鲜艳;9株菌粗蛋白含量高于60%;3株菌Rh16、Rh25、Rh34类胡萝卜素含量显著高于其他菌株(P0.05),必需氨基酸与总氨基酸的比值分别为41%、41%和40%,含有的泛醌种类为Q_(10),其中Rh16的Q_(10)含量最高,达6.49μg/mL,可以开发为水产养殖动物优良开口饵料。经培养形态、生理生化特征、16S rRNA基因序列鉴定及系统发育分析表明,菌株Rh16为粪红假单胞菌(Rhodopseudomonas faecalis)。     

A Review of Catch-and-Release Angling Mortality with Implications for No-take Reserves

Management agencies have increasingly relied on size limits, daily bag or trip limits, quotas, and seasonal closures to manage fishing in recreational and commercial fisheries. Another trend is to establish aquatic protected areas, including no-take reserves (NTRs), to promote sustainable fisheries and protect aquatic ecosystems. Some anglers, assuming that no serious harm befalls the fish, advocate allowing catch-and-release (C&R) angling in aquatic protected areas. The ultimate success of these regulations and C&R angling depends on ensuring high release survival rates by minimizing injury and mortality. To evaluate the potential effectiveness of these practices, we review trends in C&R fishing and factors that influence release mortality. Analysis of Marine Recreational Fishery Statistic Survey (MRFSS) data for 1981–1999 showed no statistically significant U.S. trends for total number of anglers (mean 7.7 × 10⁶), total catch in numbers (mean 362 × 10⁶), or total annual catch/angler (mean 42.6 fish). However, mean total annual landings declined 28% (188.5 to 135.7 × 10⁶), mean total catch/angler/trip declined 22.1% (0.95 to 0.74 fish), and mean landings/angler/trip declined 27% (0.42 to 0.31 fish). The total number of recreational releases or discards increased 97.1% (98.0 to 193.2 × 10⁶) and as a proportion of total catch from 34.2% in 1981 to 58.0% in 1999. Evidence indicates that the increased releases and discards are primarily in response to mandatory regulations and to a lesser extent, voluntary releases. Total annual catch and mean annual catch/angler were maintained despite declines in catch per trip because anglers took 30.8% more fishing trips (43.5 to 56.9 × 10⁶), perhaps to compensate for greater use of bag and size limits. We reviewed 53 release mortality studies, doubling the number of estimates since Muoneke and Childress (1994) reviewed catch and release fishing. A meta-analysis of combined data (n=274) showed a skewed distribution of release mortality (median 11%, mean 18%, range 0–95%). Mortality distributions were similar for salmonids, marine, and freshwater species. Mean mortality varied greatly by species and within species, anatomical hooking location was the most important mortality factor. Other significant mortality factors were: use of natural bait, removing hooks from deeply hooked fish, use of J-hooks (vs. circle hooks), deeper depth of capture, warm water temperatures, and extended playing and handling times. Barbed hooks had marginally higher mortality than barbless hooks. Based on numbers of estimates, no statistically significant overall effects were found for fish size, hook size, venting to deflate fish caught at depth, or use of treble vs. single hooks. Catch and release fishing is a growing and an increasingly important activity. The common occurrence of release mortality, however, requires careful evaluation for achieving fishery management goals and in some cases, disturbance, injury, or mortality may conflict with some goals of NTRs. Research is needed to develop better technology and techniques to reduce release mortality, to assess mortality from predation during capture and after release, to determine cumulative mortality from multiple hooking and release events, and to measure sub-lethal effects on behavior, physical condition, growth, and reproduction.     

Evaluation of a Questionnaire-Based Method for the Estimation of Methylmercury Exposure of Recreational Anglers in the James Bay Territory (Québec,Canada)

The impoundment of reservoirs temporarily increases the methylation of mercury bound to flooded soils and vegetation and the transfer of methylmercury (MeHg) to fish. MeHg levels in various fish species of hydroelectric reservoirs located in the James Bay territory increased by factors of 3 to 7, then gradually declined toward initial concentrations 10 to 20 years after flooding, depending on reservoir characteristics. The potential risk of increased MeHg exposure for recreational anglers who consume fish from these reservoirs had not been assessed previously. A less invasive method than systematic measurement of Hg levels in hair was developed to determine MeHg exposure of recreational anglers. A fish consumption questionnaire-based approach was combined with a toxicokinetic model to estimate the corresponding hair MeHg concentrations. The results were compared with actual analytical determinations of hair Hg levels for the 94 recreational anglers recruited for the study. The values predicted by the model based on self-reporting consumption overestimated actual hair Hg levels by an average factor greater than 6. The mean hair level predicted for the most recent period (September-October) was 23.3?µg.g^?1 compared to 3.6 µg.g^?1 for the measured value. Although the questionnaire protocol may certainly be improved to increase the precision of estimations, direct hair Hg measurement remains the more effective means to assess Hg exposure.