Growth and reproduction of female eastern and whitebelly spinner dolphins incidentally killed in the eastern tropical Pacific tuna purse-seine fishery

2009 ◽  
Vol 87 (6) ◽  
pp. 537-552 ◽  
Author(s):  
Jason P. Larese ◽  
Susan J. Chivers
Keyword(s):  
Pregnancy Rate ◽  
Tropical Pacific ◽  
Purse Seine ◽  
Calving Interval ◽  
Eastern Tropical Pacific ◽  
Population Growth Rates ◽  
Stenella Longirostris ◽  
The Mean ◽  
Spinner Dolphins ◽  
Purse Seine Fishery

Life-history parameters are estimated for two forms of the spinner dolphin ( Stenella longirostris (Gray, 1828)): the eastern subspecies ( Stenella longirostris orientalis Perrin, 1990) and the whitebelly hybrid. The data analyzed (n = 3138 eastern and 3099 whitebelly spinner dolphins) were collected between 1968 and 1994 from female dolphins incidentally killed in the yellowfin tuna ( Thunnus albacares (Bonnaterre, 1788)) purse-seine fishery that operates in the eastern tropical Pacific Ocean. Eastern spinner dolphins averaged 79.7 cm at birth, 121.5 cm at 1 year, and 171.5 cm at asymptotic length, and had a mean annual pregnancy rate of 0.351 and a calving interval of 2.84 years. Whitebelly spinner dolphins averaged 80.2 cm at birth, 122.5 cm at 1 year, and 177.1 cm at asymptotic length, and had a mean annual pregnancy rate of 0.329 and calving interval of 3.04 years. The mean age at attainment of sexual maturity was estimated to be 8.7 and 8.4 years for eastern and whitebelly spinner dolphins, respectively, which are 3.2 and 1.7 years older than those previously published. This difference indicates that the mean reproductive output during a female’s life is lower than previously expected and likely translates into lower population growth rates.

scholarly journals Mitogenomic differentiation in spinner (Stenella longirostris) and pantropical spotted dolphins (S. attenuata) from the eastern tropical Pacific Ocean

2016 ◽  
Author(s):  
Leslie Matthew S. ◽  
Archer Frederick I. ◽  
Morin Phillip A.
Keyword(s):  
Pacific Ocean ◽  
Haplotype Diversity ◽  
Morphological Diversity ◽  
Tropical Pacific ◽  
Tropical Pacific Ocean ◽  
Eastern Tropical Pacific ◽  
Stenella Longirostris ◽  
Snp Data ◽  
Subspecies Level ◽  
Spinner Dolphins

AbstractSpinner dolphins (Stenella longirostris) and spotted dolphins (S. attenuata) show high intraspecific morphological diversity and endemic subspecies in the eastern tropical Pacific Ocean (ETP). Previous studies of mitochondrial DNA (mtDNA) have found low genetic differentiation among most of these groups, possibly due to demographic factors, ongoing gene flow, and/or recent divergence. These species were heavily depleted due to bycatch in the ETP yellowfin tuna fishery. Because population structure is important for accurate management of the recovery of these species, we collected whole mitochondrial genome sequences from 104 spinner and 76 spotted dolphins to test structure hypotheses at multiple hierarchical levels. Our results showed significant differences between subspecies of spotted (FST: 0.0125; P = 0.0402) and spinner dolphins (FST: 0.0133; P = 0.034), but no support for the division of existing offshore stocks of spotted dolphins or Tres Marias spinner dolphins. We compare these results to previous results of genome-wide nuclear SNP data and suggest high haplotype diversity, female dispersal, male philopatry, or relative power of the two datasets explains the differences observed. Our results further support a genetic basis for biologically meaningful management units at the subspecies level, and provide a critical component to mitigating historical and continued fishery interactions.

scholarly journals Purse-seine vessels as platforms for monitoring the population status of dolphin species in the eastern tropical Pacific Ocean

2016 ◽  
Vol 178 ◽  
pp. 101-113 ◽  
Author(s):  
Cleridy E. Lennert-Cody ◽  
Mark N. Maunder ◽  
Paul C. Fiedler ◽  
Mihoko Minami ◽  
Tim Gerrodette ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Tropical Pacific ◽  
Purse Seine ◽  
Tropical Pacific Ocean ◽  
Population Status ◽  
Eastern Tropical Pacific

scholarly journals Effects of Lunar Phases and Other Variables on CPUE of European Pilchard, Sardina pilchardus, Caught by Purse Seine in the Eastern Mediterranean

2021 ◽  
Vol 21 (06) ◽  
pp. 283-290
Author(s):  
Zafer Tosunoglu ◽  
Tevfik Ceyhan ◽  
Ozlem Gulec ◽  
Faik Ozan Duzbastilar ◽  
Muharrem Hakan Kaykac ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Aegean Sea ◽  
Purse Seine ◽  
Sardina Pilchardus ◽  
Lunar Phases ◽  
Pelagic Fishes ◽  
The Mean ◽  
The Impact ◽  
Fishing Area ◽  
Purse Seine Fishery

European pilchard Sardina pilchardus (Walbaum, 1792) is one of the most dominant small pelagic landed by purse seine in Turkey as well as Mediterranean. In this study, we aimed to identify relationships between the seasonally adjusted CPUE and changes of the sea surface temperature (SST), fishing area, moon phase, and light used in the purse seine fishery to understand the impact of changes on the CPUE of pelagic fishes, especially S. pilchardus, by a total of 214 operations in Izmir Bay, Aegean Sea. The effect of the parameters on the Sardine CPUE, expressed in terms of kg (haul day)–1, was examined by means of the Generalized Additive Modelling (GAMs) techniques. The CPUE values for S. pilchardus were between 0 – 16 800 kg (haul day)–1 and the mean CPUE was 1 844.3±176.6 kg (haul day)–1 . The smallest median was 441 kg (haul day)–1 for full moon and the differences between the CPUE values of lunar phases were statistically significant (p<0.05). Furthermore, there is a linear relationship between CPUE and SST. In conclusion, the CPUE varied under hydrographic variables mostly SST for sardine purse seine fishery in the Aegean Sea.

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