Identification and evaluation of shark bycatch in Georgia’s commercial shrimp trawl fishery with implications for management

Abstract Many US states have recreational and commercial fisheries that occur in nursery areas occupied by subadult sharks and can potentially affect their survival. Georgia is one of few US states without a directed commercial shark fishery, but the state has a large, nearshore penaeid shrimp trawl fishery in which small sharks occur as bycatch. During our 1995–1998 investigation of bycatch in fishery‐dependent sampling events, 34% of 127 trawls contained sharks. This bycatch totalled 217 individuals from six species, with Atlantic sharpnose shark, Rhizoprionodon terraenovae (Richardson), the most common and finetooth shark, Carcharhinus isodon (Müller & Henle) and spinner shark, Carcharhinus brevipinna (Müller & Henle), the least common. The highest catch rates for sharks occurred during June and July and coincided with the peak months of the pupping season for many species. Trawl tow speed and tow time did not significantly influence catch rates for shark species. Gear configurations [net type, turtle excluder device (TED), bycatch reduction device] affected catch rates for shark species. Results of this study indicate gear restrictions, a delayed season opening, or reduced bar spacing on TEDs may reduce shark bycatch in this fishery.     

Variations in body condition of green turtles (Chelonia mydas) in two nearby foraging grounds indicate their sensitivity to foraging habitats

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Estimation of temporal changes in the growth of green turtles <Emphasis Type="Italic">Chelonia mydas</Emphasis> in waters around the Ogasawara Islands

Biological and life-cycle information is essential to any fisheries management program. We have investigated temporal changes in growth parameters in the von Bertalanffy growth curve for green turtles, Chelonia mydas, in waters around the Ogasawara Islands. The variance model of individual variability of growth used in our study was one derived from the stochastic differential equation with the white noise of constant intensity. Maximum likelihood estimates of the parameters were made using the data of 102 recovery records of tagging experiments from 1974 to 1995. The estimations were carried out for each of two models of linear and sudden changes in the parameters, and the best model was selected using Akaike's information criterion. The selected model was that all of the parameters excepting asymptotic straight carapace length were linear functions of year and that the asymptotic length was constant over the years. The estimated values of the growth coefficient in 1974 and 1995 were 0.0317 and 0.192 per year, respectively, and the estimated value of the asymptotic straight carapace length was 97.2 cm. Implications of the results and future issues to be resolved in near future are discussed.     

Movements and behaviors of swordfish Xiphias gladius in the United States Pacific Leatherback Conservation Area

This study reports on the movements of swordfish tagged within the Pacific Leatherback Conservation Area (PLCA), an expansive region (>500,000 km²) off the U.S. West Coast that has been seasonally restricted to drift‐gillnet fishing since 2001 to reduce leatherback sea turtle (Dermochelys coricea) interactions. Thirteen swordfish were outfitted with satellite‐linked archival tags scheduled for short (2–20 days, n = 11) and longer‐term (150 days, n = 2) data collection. All tags were deployed on basking swordfish using traditional harpoon‐based methods during the fall of 2012–2013, near offshore seamounts (35.6°N/122.9°W to 37.4°N/123.5°W). Depth and temperature data from 11 swordfish (~90 to 150 kg) resulted in <251 days of movement information from the PLCA region. All tagged individuals exhibited surface‐oriented nocturnal movements, spending >99% of the night above the average thermocline depth (37.5 m), with an average night depth of 8.3 ± 1.6 m. Daytime depth distribution was greater and more variable (mean 107.1 ± 21.2 m), with fish primarily displaying three behavioral patterns: (i) basking activity, 16.7% of the day, (ii) a mixed‐layer distribution between 3 m and the thermocline (26.8% of the day), and (iii) prolonged dives below the thermocline, 56.5% of the day. For seven of the tracks, daytime basking rates increased when thermocline depth was <37 m. As fish moved offshore, there was less variability in vertical movements with a reduction in both basking activity and mixed layer occupancy, as well as an increase in average daytime depth. These data are discussed with respect to the potential development of alternative fishery options for the PLCA.     

海洋捕捞误捕海龟问题及其管理研究

海龟是海洋生态系统的重要组成部分,世界现存海龟仅有2科6属7种,且都处于濒危状态,国际上十分重视海龟保护工作。在海洋渔业捕捞活动中,经常误捕到海龟,捕虾拖网、刺网、延绳钓渔业对海龟资源的误捕和伤害性最大。目前,国际上已形成了以联合国粮农组织(FAO)为主导,各区域性渔业组织及捕鱼国政府部门为管理主体的法律政策框架,制定通过了一系列有关海龟养护、减少海龟误捕及伤害的决议性文件。主要的管理手段有:渔民培训、渔具渔法优化设计、信息收集与交流、港口检查措施、观察员制度、规范渔捞日志等。在技术措施方面,拖网捕捞中的"海龟逃生装置"、刺网捕捞中的"窄网"和提高拉杆长度、延绳钓渔业中采用的圆形钓钩和鲐鱼饵料,都产生了积极的效应。我国的渔业管理制度对减少渔业活动中的海龟误捕伤害涉及不多,研究很少,缺乏具体的法律法规来指导,亟需完善。建议:(1)普及基于生态系统的渔业管理方法和理念;(2)不断加强信息交流与合作;(3)制定可行的管理标准,并使用市场机制;(4)相应的控制手段要适当,并与其他措施相结合;(5)渔民培训与保育观念的宣传。我国已经开始重视发展可持续性渔业,为进一步规范海洋捕捞、减少对海龟等珍稀物种的伤害误捕提供了契机,如何与国际社会的管理"接轨",实现海洋生物多样性与渔民生计的"双赢",都是需要管理部门着重考虑的。     

龟苓蔓越莓保健果冻的研制

为研制风味良好、营养丰富的保健型果冻,以龟苓膏粉、蔓越莓(Oxycoccos)为主要原料,开发龟苓蔓越莓营养果冻,采用单因素试验及正交试验确定最佳配方。结果表明,以龟苓膏粉6 g、果冻粉0.7 g、白砂糖8 g、蜂蜜10 g、水150 m L为最佳配方,按此配方制得的营养果冻呈黑褐色,质地均匀,口感光滑细腻、富有弹性,总体感官品质优良。开发此营养果冻,符合当代消费者的健康饮食理念,具有较高的实际应用价值。     

Pharmacokinetics of marbofloxacin after a single oral dose to loggerhead sea turtles (Caretta caretta)

The single-dose disposition kinetics of marbofloxacin (MBX) were determined in clinically healthy loggerhead sea turtles (n = 5) after oral (PO) administration of 2 mg kg⁻¹ bodyweight. Marbofloxacin plasma concentrations were determined by DAD–HPLC (LOD/LOQ 0.015/0.05 μg ml⁻¹). Data were subjected to non-compartmental analysis. Following PO administration, marbofloxacin achieved maximum plasma concentrations of 11.66 ± 2.53 mg L⁻¹ at 15.00 ± 3.00 h. The absence of general adverse reactions in the turtles of the study, and the favourable pharmacokinetic properties (long half-life and high maximum plasma concentration) of MBX administered PO at the single-dose of 2 mg kg⁻¹ suggest the possibility of its safe and effective clinical use in loggerhead sea turtles.     

木薯叶提取液制备及其对甲鱼生长的影响

本研究优化了木薯叶提取液制备的条件,并且检测该提取液对甲鱼生长性能、血液化学指标的影响。试验首先对提取木薯叶的溶剂提取法进行工艺优化,确定最优提取条件,包括：溶剂浓度、料液比、提取温度、提取时间4个因素。其次将提取液经处理后加入甲鱼饲料中,通过分析检测甲鱼存活率、生长性能、饲料转化性能、机体营养组成、血液生化及免疫能力指标,来确定其对甲鱼生长的影响。试验结果表明,木薯叶提取制备的最优工艺为：乙醇浓度50％,料液比（mL/g)40 ∶ 1,提取温度70 ℃,提取时间2 h;通过对甲鱼饲养的研究,表明饲料中添加木薯叶提取液能提高甲鱼的生长速度,降低饲料系数,并能降低甲鱼机体内血糖、胆固醇、甘油三酯水平,以及降低血清丙二醛含量,从而提高了甲鱼的糖代谢、脂肪代谢和免疫能力。因此,本研究不仅首次将木薯叶提取液作为添加剂加入甲鱼饲料,同时也为木薯叶提取液作为天然低毒的饲料添加剂提供了理论依据。     

High survivorship of an annually decreasing aggregation of hawksbill turtles,Eretmochelys imbricata,found foraging in the northern Great Barrier Reef

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