Harbour porpoise Phocoena phocoena abundance in the southwestern Baltic Sea
Harbour porpoise Phocoena phocoena abundance in the southwestern Baltic Sea
复制标题
DOI：
10.3354/esr00161
复制
发表时间：
2008-01-01
影响因子：
3.1
通讯作者：
Siebert, U.
中科院分区：
文献类型：
--
作者：
Scheidat, M.;Gilles, A.;Siebert, U.
港豚Phocoena Phocoena是唯一生活在波罗的海的鲸目动物物种。这一地区至少有两个不同的亚群，在波罗的海西部有一条假定的分界线。2002年至2006年，在不同季节进行了航空调查，以估计波罗的海西南部的江豚数量。在调查区域内，共划分出3个地层。总共完成了对这些地层的46次调查。对于每一次调查，分别计算了每一层的丰度估计值和相应的可信区间(CI)。各区域之间的密度在季节和空间上有所不同，西部研究区域(基尔比特)通常显示出最高的密度。当连续25天内覆盖所有3个地层时，计算整个调查区的丰度。有10项调查符合这些标准。波罗的海西部的总体丰度因调查而异，最低值在2003年3月(457个；95%CI：0至1632)，最高估计值在2005年5月(4610个；95%，CI：2259至9098)。所有其他调查的结果都在1,352至2,905ind之间，有很大程度上重叠的可信区间。应用目前德国波罗的海地区唯一可用的兼捕估计(其中没有测量精确度)，波罗的海西部江豚兼捕的百分比在当地人口的1.78%到17.94%之间。为了提高副渔获率的精确度，需要对该区域进行更详细的副渔获量估计。然而，结果表明，副渔获物是波罗的海西部港口江豚的主要威胁。
Harbour porpoise Phocoena phocoena is the only cetacean species resident in the Baltic Sea. At least 2 different, subpopulations occur in this area, with a presumed demarcation line in the western Baltic Sea, Aerial surveys were conducted during different seasons in the years 2002 to 2006, to obtain estimates of porpoise abundance for the southwestern Baltic. Within the survey area, 3 strata were defined. In total, 46 surveys were completed for these strata. Abundance estimates and corresponding confidence intervals (Cl) were calculated for each stratum separately for each survey. Density between areas varied seasonally and spatially, with the western study area (Kiel Bight) generally showing the highest density. Whenever all 3 strata were covered within 25 consecutive days, abundance for the overall survey area was calculated. Ten surveys met these criteria. Overall abundance in the western Baltic varied between surveys, with the lowest value in March 2003 (457 ind.; 95% CI: 0 to 1632), and the highest estimate in May 2005 (4610 ind.; 95%, Cl: 2259 to 9098). The results of all other surveys were in the range from 1352 to 2905 ind., with largely overlapping confidence intervals. Applying the only available bycatch estimates (which include no measure of precision) currently available for the German Baltic region, the percent of porpoise bycatch in the western Baltic lies within a range of 1.78 to 17.94% of the local population. To increase the precision of bycatch rates, more detailed bycatch estimates for this region are needed. Nevertheless, the results indicate that bycatch is a major threat to harbour porpoises throughout the western Baltic Sea.