Shad Species Research Articles

Length-weight and length-length relationships for four shad species along the western Black Sea coast of Turkey

Summary This study investigates length–weight and length–length relationships of four shad species (Alosa caspia caspia, Alosa immaculata, Alosa maeotica, Alosa tanaica) captured in the western Black Sea coast of Turkey. A total of 686 specimens, 355 females and 331 males, were caught by gill net, trammel net and longline from 2006 through 2007 along the western Black Sea coast of Turkey. The relationships of total length (TL), fork length (FL) and standard length (SL) are presented for inhabiting in the Black Sea four shad species and the relationships between total length (TL) and body weight (BW) from the two localities, Sile and Karasu in the western Black Sea coast of Turkey. The Length–weight relationships generally indicated positive allometric growth in Alosa species for both males and females and an isometric growth for A. immaculata females. The coefficient b ranged from a minimum 2.97 for females of A. immaculata to a maximum 3.75 for both sexes A. c. caspia. Results indicated that the length–length relationship between the three length measurements were highly correlated (r2 > 0.99, P < 0.001).

A Review and Updated Assessment of Florida's Anadromous Shads: American Shad and Hickory Shad

AbstractThis paper reviews the history of fishing, regulations, and stock assessments for Florida's anadromous shad species—American shad Alosa sapidissima and hickory shad A. mediocris—and assesses their status in Florida's St. Johns River based on a creel survey and an electrofishing survey. Historically, these anadromous shads constituted an important fishery in Florida. Landings were first reported in the 1860s, and scientific assessments occurred in the 1950s, 1960s, and early 1970s. Netting restrictions effectively ended the commercial fishery in the 1990s. We used recreational catch rates as a proxy for stock size and found it to be low but stable during 1993–2005. The mean length of American shad was significantly less during 2002–2005 than it was historically (1958), and the recent proportions of female American and hickory shad were significantly lower than the historical proportions. These data were interpreted as demonstrating a negative, but perhaps only an historical, effect of fishing. The rebuilding of Florida's anadromous shad stocks via fishing regulations was not evident; this may require more time, or perhaps factors other than fishing are interfering with the rebuilding process.

SHAD SPECIES IN GREEK WATERS – AN HISTORICAL OVERVIEW AND PRESENT STATUS.

SUMMARY An historical overview of the shad species in Greek waters and the present status of these species are given. The species Alosa fallax (Lacepede, 1803), Alosa macedonica (Vinciguerra, 1921) and Alosa vistonica (Economidis and Sinis, 1986), are the three kinds of shad thriving in Greek waters. The Alosa fallax regularly occurs across coastal zones, mainly near estuaries, and enters the rivers such as Evros, Nestos, Strymon (Thrace and Macedonia), Pinios (Thessaly), Acheloos and Thyamis (western Greece), during the spawning period. Its presence is also confirmed in lake Vistonis, which is connected with the Thracian Sea and there is also strong evidence that it enters some other rivers such as Loudias (Macedonia), Louros and Arachthos (western Greece). Alosa macedonica is a landlocked species endemic to lake Volvi, whereas Alosa vistonica is also endemic and landlocked in the lacustrine part of the lagoon Vistonis.

Factors related to gizzard shad and the threadfin shad occurrence and abundance in Florida lakes

Gizzard shad Dorosoma cepedianum were collected in 23 and threadfin shad D. petenense were collected in 22 of the 60 Florida lakes sampled. Logistic regression equations were 94% effective for predicting gizzard shad occurrence from chlorophyll and lake surface area, and 84% effective for predicting threadfin shad occurrence from lake surface area and lake volume inhabited (PVI). Occurrence of both shad species was related positively to lake size. In lakes where gizzard shad or threadfin shad were collected, shad density and biomass of both shad species were related positively to chlorophyll. Gizzard shad populations were generally vulnerable to predation in lakes, with the per cent of gizzard shad ≤200mm LT values exceeding 60% with few exceptions. Effects of gizzard shad and threadfin shad on fish community dynamics may be confined to relatively large (&gt;100 ha) and fertile (chlorophyll &gt;20–30μg l−1) Florida lakes.

Evaluation of Gill-Net Sampling for Estimating Abundance and Length Frequency of Reservoir Shad Populations

Horizontal and vertical gill nets were used to intensively sample gizzard shad Dorosoma cepedianam and threadfin shad D. petenense in Lake Texoma, Texas–Oklahoma, in August 1991. We evaluated spatial patterns, sampling precision, mesh-size selectivity, and sample sizes required to detect differences in shad abundance. Abundance patterns differed among species, length-groups, and sampling sites. Age-0 shad occurred mainly near the surface, whereas older fish were more evenly distributed over depth. Spatial variation in abundance was more pronounced among embayments than between nearshore and offshore sites within embayments. Spatial aggregation of shad was similar to that reported for a variety of other aquatic organisms, suggesting that experimental designs for gill-net surveys should incorporate statistical approaches similar to those used in other sampling programs. With horizontal gill nets, investigators can estimate median catch rate (number per net) within 25% of the true median with 95% certainty by using 37 or fewer nets, provided that the variance of the log10-transformed catch data is 0.09 (the median observed variance) or less. At the maximum observed variance (0.55), 4–20 gill nets would be required for a t-test to detect a twofold difference between two independent density estimates at ∝ = 0.05 and power (1 – β) = 0.95. Catch data in vertical gill nets produced less precise abundance estimates, and length frequencies of shad collected in the same mesh sizes differed between horizontal and vertical nets. Estimates of mesh-size retention probabilities, based on relations between shad girth and net mesh perimeter, were used to determine mesh sizes needed for efficient sampling of a wide range of sizes of both shad species. Mesh sizes recommended for sampling shad (55–380 mm) collected at Lake Texoma ranged from 8- to 51-mm-bar measure.

Assessing the Potential for Direct Feeding Interactions among Larval Black Bass and Larval Shad in Two Southeastern Reservoirs

Abstract We quantified diets of larvae of black bass Micropterus spp., threadfin shad Dorosoma petenense, and gizzard shad D. cepedianum in two Alabama reservoirs, and sampled limnetic and littoral crustacean zooplankton to evaluate the potential for feeding competition. Diet overlap between larval black bass and larval shad never exceeded 17%, was less than 5% on 12 of 14 sample dates, and was greatest early, when zooplankton was most abundant. Copepod nauplii and cyclopoid copepods were responsible for over 95% of the diet overlap between larval bass and shad; however, larval black bass consumed longer individuals within both prey taxa than did either shad species. Further, the timing of greatest diet overlap was during peak zooplankton abundance. We conclude that direct negative feeding interactions among larval shad and larval black bass are of little biological importance.

Genetic polymorphism of adenosine deaminase (ADA; E.C. 3.5.4.4.) in allis shad, Alosa alosa and twaite shad, Alosa fallax

A genetic polymorphism of adenosine deaminase (ADA), is described for the first time in European shad species, Alosa alosa and Alosa fallax. Significant heterogeneity in gene frequencies was found, both between species and within species.