Age and growth of the shortfin mako (Isurus oxyrinchus) in the south-eastern Pacific off Chile

2009 ◽  
Vol 60 (5) ◽  
pp. 394 ◽  
Author(s):  
Francisco Cerna ◽  
Roberto Licandeo
Keyword(s):  
Growth Parameters ◽  
Eastern Pacific ◽  
Age And Growth ◽  
The South ◽  
Age Classes ◽  
Vertebral Centra ◽  
South Eastern ◽  
Isurus Oxyrinchus ◽  
Shortfin Mako ◽  
Longline Fisheries

The shortfin mako, Isurus oxyrinchus, is a large pelagic shark with a widespread global distribution. However, very little is known about most aspects of this species for the south-eastern Pacific. In the present paper, the age and growth parameters of the shortfin mako, caught by Chilean swordfish longline fisheries from 2004 to 2005, are reported. Ages were estimated by counting band-pairs from sections of vertebral centra from 547 individuals, ranging from 76 to 330 cm in total length (TL). Trends in the proportion of opaque edges for all ages combined and grouped into ages 0–6 and 7–26 years indicated that they are formed during summer and showed that annually, one band-pair is formed in the vertebrae of shortfin makos. Modal-progression analysis was used to verify the first three age classes (ages 0–2 years). For both sexes, the oldest estimated age was 25+ years. Von Bertalanffy growth parameters were estimated at L∞ = 325.29 cm TL, K = 0.076 year–1 and t0 = –3.18 years for females and L∞ = 296.60 cm TL, K = 0.087 year–1 and t0 = –3.58 years for males. The results indicated that this species is highly vulnerable to exploitation and, thus, urgent conservation measures are required.

Morphometrical and molecular evidence suggests cryptic diversity among hookworms (Nematoda: Uncinaria) that parasitize pinnipeds from the south-eastern Pacific coasts

2018 ◽  
Vol 94 ◽  
Author(s):  
M.T. González ◽  
Z. López ◽  
J.J. Nuñez ◽  
K.I. Calderón-Mayo ◽  
C. Ramírez ◽  
...  
Keyword(s):  
Large Subunit ◽  
Principal Component ◽  
Eastern Pacific ◽  
Lsu Rdna ◽  
Molecular Evidence ◽  
South American ◽  
Southern Chile ◽  
The South ◽  
South Eastern ◽  
Neophoca Cinerea

AbstractHookworms of the genus Uncinaria parasitize pinniped pups in various locations worldwide. Four species have been described, two of which parasitize pinniped pups in the southern hemisphere: Uncinaria hamiltoni parasitizes Otaria flavescens and Arctocephalus australis from the South American coast, and Uncinaria sanguinis parasitizes Neophoca cinerea from the Australian coast. However, their geographical ranges and host specificity are unknown. Uncinaria spp. are morphologically similar, but molecular analyses have allowed the recognition of new species in the genus Uncinaria. We used nuclear genetic markers (internal transcribed spacer (ITS) and large subunit (LSU) rDNA) and a mitochondrial genetic marker (cytochrome c oxidase subunit I (COI)) to evaluate the phylogenetic relationships of Uncinaria spp. parasitizing A. australis and O. flavescens from South American coasts (Atlantic and Pacific coasts). We compared our sequences with published Uncinaria sequences. A Generalized Mixed Yule Coalescent (GMYC) analysis was also used to delimit species, and principal component analysis was used to compare morphometry among Uncinaria specimens. Parasites were sampled from A. australis from Peru (12°S), southern Chile (42°S), and the Uruguayan coast, and from O. flavescens from northern Chile (24°S) and the Uruguayan coast. Morphometric differences were observed between Uncinaria specimens from both South American coasts and between Uncinaria specimens from A. australis in Peru and southern Chile. Phylogenetic and GMYC analyses suggest that south-eastern Pacific otariid species harbour U. hamiltoni and an undescribed putative species of Uncinaria. However, more samples from A. australis and O. flavescens are necessary to understand the phylogenetic patterns of Uncinaria spp. across the South Pacific.

Phytoplankton Production in the South-eastern Pacific

Nature ◽  
1963 ◽  
Vol 200 (4901) ◽  
pp. 87-88 ◽  
Author(s):  
ERIC D. FORSBERGH ◽  
JAMES JOSEPH
Keyword(s):  
Eastern Pacific ◽  
Phytoplankton Production ◽  
The South ◽  
South Eastern

Age and growth of blue grenadier, Macruronus novaezelandiae (Hector), in south-eastern Australian waters

1987 ◽  
Vol 38 (5) ◽  
pp. 625 ◽  
Author(s):  
TJ Kenchington ◽  
O Augustine
Keyword(s):  
Growth Parameters ◽  
Growth Curves ◽  
Growth Patterns ◽  
Age And Growth ◽  
Double Blind ◽  
Blind Test ◽  
Thin Sections ◽  
South Eastern ◽  
Weight Data ◽  
Immature Fish

Blue grenadier, Macruronus novaezelandiae, from south-eastern Australian waters were aged, using their otoliths (whole and in transverse thin sections). The greatest recorded age was 25 years. A double blind test showed that the recorded ages were sufficiently reproducible to use in fitting growth curves (Index of Average Percent Error: 8%), but not sufficiently so to assign individuals to particular year-classes. Von Bertalanffy growth curves were fitted to both length and weight data. For males, Lt = 90.7 (1 - exp[-0.256(t + 1.21)]} and Wt = 2.62 (1 - exp[-0.277(t + 1.39)]}3. For females, Lt = 99.3 {l - exp[-0.203(t + 1.48)]} and Wt = 4.16{1 - exp[-0.157(t + 2.93)]}3. L is the length in centimetres, W is the weight in kilograms and t is the age in years. A comparison with length-frequency modes validated the growth curves for immature fish, but no validation was possible for the adults. The $exes have qignificantly different growth patterns. Their growth parameters are typical of those of commercially exploited, temperate gadoid fishes and show no modification for the deep-water zone inhabited by blue grenadier.

scholarly journals Discovering sounds in Patagonia, characterizing sei whale (<i>Balaenoptera borealis</i>) downsweeps in the south-eastern Pacific Ocean

2018 ◽  
Author(s):  
Sonia Español-Jiménez ◽  
Paulina A. Bahamonde ◽  
Gustavo Chiang ◽  
Verena Häussermann
Keyword(s):  
Pacific Ocean ◽  
Peak Frequency ◽  
Eastern Pacific ◽  
Absolute Maximum ◽  
Maximum Frequency ◽  
Eastern Pacific Ocean ◽  
The South ◽  
South Eastern ◽  
Average Maximum ◽  
The Absolute

Abstract. Sei whales (Balaenoptera borealis) is the least known whale species. Information on sei whale´s vocalizations in the south-eastern Pacific Ocean and its regional variability are even more scarce than that from other ocean areas. This research presents the first characterization of sei whale sounds recorded in Chile during austral autumn of 2016 and 2017. A total of 41 calls have been attributed to sei whale’s downsweeps. In 2016, calls ranged from an average maximum frequency of 105.3 Hz down to an average minimum 35.6 Hz over 1.6 s with a peak frequency of 65.4 Hz. During 2017, calls ranged from an average maximum frequency of 93.3 Hz down to 42.2 Hz (over 1.6 s) with a peak frequency of 68.3 Hz. The absolute minimum frequency recorded was 30 Hz and the absolute maximum frequency was 129.4 Hz. Calls generally occurred in pairs, but triplets or singles were also registered. These low frequency sounds share characteristics with recordings of sei whales near the Hawaii Islands, but with differences in the maximum frequencies and duration. These calls distinctly differ from sounds previously described for sei whales in the Southern Ocean and are the first documented sei whale calls in the South-eastern Pacific.

Heat-Flow Values from the South-Eastern Pacific

Nature ◽  
1959 ◽  
Vol 183 (4665) ◽  
pp. 882-883 ◽  
Author(s):  
R. Von HERZEN
Keyword(s):  
Heat Flow ◽  
Eastern Pacific ◽  
The South ◽  
South Eastern
Sign in / Sign up

Export Citation Format

Share Document