Age, growth, and mortality of wahoo, Acanthocybium solandri, from the Atlantic coast of Florida and the Bahamas

2008 ◽  
Vol 59 (9) ◽  
pp. 799 ◽  
Author(s):  
Richard S. McBride ◽  
Adam K. Richardson ◽  
Kristin L. Maki
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic Ocean ◽  
Growth Parameters ◽  
Atlantic Coast ◽  
Fork Length ◽  
First Year ◽  
The Bahamas ◽  
Western Atlantic ◽  
Large Size ◽  
The 1960S

Wahoo, Acanthocybium solandri, constitute an economically important fishery for many coastal nations, but assessment of this living marine resource is hampered by a lack of basic life history information. The present study demonstrates that wahoo in the western North Atlantic Ocean are short lived, grow rapidly in their first year, achieve a very large size, and have high mortality rates. The largest individuals were female and the sex ratio was significantly female-biased (298 females: 223 males: 54 unknown sex). An edge analysis showed that annuli formed primarily during winter–spring, which supported the use of sectioned otoliths for ageing wahoo. Wahoo lived a median of 1.3 years, a mean of 1.8 years, and a maximum of 9.3 years (n = 469). They had a high instantaneous mortality rate (Z = 0.98), and they grew rapidly and to a large size; von Bertalanffy growth parameters were: L∞ = 1701 mm fork length (FL), K = 0.381, to = –1.63. Females had a very similar maximum age relative to males (maximum age 9.3 v. age 9.1 years), and they had a slightly, but not significantly, lower mortality (Z = 0.91 v. 1.1) than males. Females grew slightly, although not significantly, larger than males (L∞ = 1797 v. 1555 mm FL, maximum observed = 1804 v. 1585 mm FL). Presumably the piscivorous nature of wahoo feeding, as noted by others, fuels these fast growth rates. Comparative data are very limited but it appears that the survival rate of wahoo in the western Atlantic Ocean is not different now than in the 1960s.

The wet deposition of trace metals to the western atlantic ocean at the mid-atlantic coast and on Bermuda

1984 ◽  
Vol 18 (12) ◽  
pp. 2657-2664 ◽  
Author(s):  
T.M. Churc ◽  
J.M. Tramontano ◽  
J.R. Scudlark ◽  
T.D. Jickells ◽  
J.J. Tokos ◽  
...  
Keyword(s):  
Trace Metals ◽  
Atlantic Ocean ◽  
Wet Deposition ◽  
Atlantic Coast ◽  
Western Atlantic ◽  
Western Atlantic Ocean

scholarly journals Hybridization between sympatric hammerhead sharks in the western North Atlantic Ocean

2019 ◽  
Vol 15 (4) ◽  
pp. 20190004 ◽  
Author(s):  
Amanda M. Barker ◽  
Douglas H. Adams ◽  
William B. Driggers ◽  
Bryan S. Frazier ◽  
David S. Portnoy
Keyword(s):  
Atlantic Ocean ◽  
First Generation ◽  
North Atlantic Ocean ◽  
Western Atlantic ◽  
Sphyrna Lewini ◽  
Scalloped Hammerhead ◽  
Wide Range ◽  
Hammerhead Sharks ◽  
Conservation Concern ◽  
Globally Distributed

Hybridization between closely related species has been documented across a wide range of taxa but has not been well studied in elasmobranchs. Hammerhead sharks have drawn global conservation concern because they experience some of the highest mortality rates among sharks when interacting with fisheries. Here we report on the detection of hybrids between the globally distributed scalloped hammerhead ( Sphyrna lewini ) and recently described Carolina hammerhead ( S. gilberti ) which are only known from the western Atlantic Ocean. Using a genomics approach, 10 first-generation hybrids and 15–17 backcrosses were detected from 554 individuals. The identification of backcrosses demonstrates hybrids are viable, and all backcrosses but one involved a scalloped hammerhead. All hybrids but one possessed Carolina hammerhead mtDNA, indicating sex-biased gene flow between species. Repeated hybridization and backcrossing with scalloped hammerheads could lead to the loss of endemic Carolina hammerheads.

Reproductive biology of wahoo, Acanthocybium solandri, from the Atlantic coast of Florida and the Bahamas

2009 ◽  
Vol 60 (9) ◽  
pp. 893 ◽  
Author(s):  
Kristin L. Maki Jenkins ◽  
Richard S. McBride
Keyword(s):  
Egg Production ◽  
Significant Contribution ◽  
Atlantic Coast ◽  
Fork Length ◽  
Economic Importance ◽  
Reproductive Seasonality ◽  
The Bahamas ◽  
Spawning Frequency ◽  
History Information ◽  
Ovulatory Follicles

Despite its economic importance to many coastal nations, assessments of wahoo, Acanthocybium solandri, are hampered by a lack of basic life history information. In this study, wahoo were collected from Florida’s Atlantic coast and the northern Bahamas during 1997–2006 to examine reproductive seasonality, maturation, spawning frequency and fecundity. These samples demonstrated only a single, summer-spawning season, which did not support earlier postulations of spring spawning by wahoo near the Bahamas. The size and age at 50% female maturity were 925 mm fork length and 0.64 years, respectively. Spawning frequency was, on average, every 5 days during June–August, but 13% of mature females were inactive during this period. Batch fecundity was positively correlated with fish size, and varied between 0.44 and 1.67 million eggs. Parasites, previously unreported to occur in wahoo gonads and identified only as philometrid nematodes, were evident in 11% of these females. Most parasitised fish had vitellogenic oocytes, several even with oocytes with migrating nuclei or post-ovulatory follicles, so these parasitised fish were capable of spawning. Although wahoo have been noted to have relatively small gonads, and parasites are often found in female gonads, annual fecundity estimates are of the order of 10–100 million eggs. The significant contribution of older, larger females to egg production should be considered in managing this fishery.

First record of Piscicapillaria bursata (Nematoda: Capillariidae), a parasite of hammerhead sharks Sphyrna spp., in the western Atlantic Ocean

2020 ◽  
Vol 138 ◽  
pp. 133-136 ◽  
Author(s):  
F Moravec ◽  
KM Dalrymple ◽  
AS Galloway ◽  
AM Barker ◽  
I de Buron
Keyword(s):  
South Carolina ◽  
Atlantic Ocean ◽  
Atlantic Coast ◽  
First Record ◽  
New Host ◽  
Western Atlantic ◽  
Western Atlantic Ocean ◽  
Scalloped Hammerhead ◽  
Hammerhead Sharks ◽  
New Host Species

Examination of 32 spiral valves from neonate specimens of hammerhead shark Sphyrna spp. (Carcharhiniformes: Sphyrnidae) captured between June and August 2018 off the Atlantic coast of South Carolina, USA, revealed the presence of the capillariid nematode Piscicapillaria bursata (Capillariidae) in the Carolina hammerhead S. gilberti, the scalloped hammerhead S. lewini, and their hybrids. This is the second find of this parasite originally described from hammerhead sharks off Australia, its first record from the western Atlantic Ocean, and its first record in a new host species and in hybrids.

Age and growth of the scalloped hammerhead shark, Sphyrna lewini, in the north-west Atlantic Ocean and Gulf of Mexico

2007 ◽  
Vol 58 (1) ◽  
pp. 34 ◽  
Author(s):  
Andrew N. Piercy ◽  
John K. Carlson ◽  
James A. Sulikowski ◽  
George H. Burgess
Keyword(s):  
Atlantic Ocean ◽  
Gulf Of Mexico ◽  
Growth Parameters ◽  
Fork Length ◽  
Age And Growth ◽  
North West ◽  
Scalloped Hammerhead ◽  
The North ◽  
The Usa ◽  
Cent Error

The scalloped hammerhead, Sphryna lewini (Griffith & Smith, 1834), is a globally exploited species of shark. In order to gain insight into the life history of this species in the USA waters, age and growth was examined from specimens (n = 307) captured from the north-west Atlantic Ocean and from the Gulf of Mexico. The von Bertalanffy growth model resulted in growth parameters of L∞ = 214.8 cm fork length (FL), k = 0.13 year–1, t0 = –1.62 year for males and L∞ = 233.1 cm FL, k = 0.09 year–1, t0 = –2.22 year for females. The oldest age estimates obtained for this population were 30.5 years for both males and females, which corresponded to FL of 234 cm and 241 cm respectively. Bowker’s test of symmetry and Index of Average Per Cent Error suggests that our ageing method represents a non-biased and precise approach to the age assessment. Marginal increments were significantly different between months (Kruskal–Wallis P = 0.017) with a distinct trend of increasing monthly increment growth beginning in January. When compared to previously published studies, our growth estimates suggest slower growth than populations in the Pacific Ocean but faster growth than previously reported in the Gulf of Mexico.

Cooling and freshening of the subpolar North Atlantic Ocean since the 1960s

Nature ◽  
1992 ◽  
Vol 360 (6399) ◽  
pp. 55-57 ◽  
Author(s):  
J. F. Read ◽  
W. J. Gould
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
The 1960S

scholarly journals An Anatomy of the Cooling of the North Atlantic Ocean in the 1960s and 1970s

2014 ◽  
Vol 27 (21) ◽  
pp. 8229-8243 ◽  
Author(s):  
Daniel L. R. Hodson ◽  
Jon I. Robson ◽  
Rowan T. Sutton
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Meridional Overturning Circulation ◽  
Subpolar Gyre ◽  
Considerable Uncertainty ◽  
The North ◽  
The North Atlantic ◽  
1960S And 1970S ◽  
The 1960S

Abstract In the 1960s and early 1970s, sea surface temperatures in the North Atlantic Ocean cooled rapidly. There is still considerable uncertainty about the causes of this event, although various mechanisms have been proposed. In this observational study, it is demonstrated that the cooling proceeded in several distinct stages. Cool anomalies initially appeared in the mid-1960s in the Nordic Seas and Gulf Stream extension, before spreading to cover most of the subpolar gyre. Subsequently, cool anomalies spread into the tropical North Atlantic before retreating, in the late 1970s, back to the subpolar gyre. There is strong evidence that changes in atmospheric circulation, linked to a southward shift of the Atlantic ITCZ, played an important role in the event, particularly in the period 1972–76. Theories for the cooling event must account for its distinctive space–time evolution. The authors’ analysis suggests that the most likely drivers were 1) the “Great Salinity Anomaly” of the late 1960s; 2) an earlier warming of the subpolar North Atlantic, which may have led to a slowdown in the Atlantic meridional overturning circulation; and 3) an increase in anthropogenic sulfur dioxide emissions. Determining the relative importance of these factors is a key area for future work.

Gambia (The)

2020 ◽  
Author(s):  
Marius Schneider ◽  
Vanessa Ferguson
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Atlantic Coast ◽  
Working Hours ◽  
Cape Verde ◽  
The Gambia ◽  
The North ◽  
The North Atlantic ◽  
The Republic

The Gambia, officially known as the Republic of Gambia, is the smallest country in Africa, with a total area of 11,295 square kilometres (km) and with a population of 2.101 million. The Gambia has an 80 km coastline bordering the North Atlantic Ocean and geographically surrounded by Senegal by land and Cape Verde by sea. Banjul, the capital, and Serekunda, the largest city, are located at the mouth of the Gambia River along the Atlantic Coast. Official working hours are 0800 to 1600 from Monday to Friday and 0800 to 1230 on Fridays. The currency in Gambia is the Gambian dalasi (GMD) and the country is primarily a cash-based economy.

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