KARADENİZİN FARKLI AV SAHALARINDA DEMERSAL TROL İLE AVLANAN MEZGİT (Merlangius merlangus euxinus, N.) VE BARBUNYA (Mullus barbatus ponticus, E.) BALIKLARININ AV MİKTARLARI VE BOY KOMPOZİSYONLARININ KARŞILAŞTIRILMASI

Predictions concerning the effect of seals upon prey stocks require an understanding of temporal variations in diet composition. This study examined the extent of between-year and seasonal variations in the diet of harbour seals (Phoca vitulina) from the Moray Firth, Scotland, between 1989 and 1992. Analyses of fish otoliths and cephalopod beaks collected from 1129 faecal samples were used to derive estimates of the contribution made by each of 35 prey species, based on the number and mass consumed. The key prey, by mass, were sand eels (Ammodytidae) (47%), lesser octopus (Eledone cirrhosa) (27%), whiting (Merlangius merlangus) (6%), flounder (Platichthys flesus) (5%), and cod (Gadus morhua) (4%). Between-year and seasonal fluctuations in the contributions of these species were observed. Sand eels contributed 86–20% in summer and 91–49% in winter. Lesser octopus contributed 0–62% in summer and < 5% in winter, whilst whiting and cod contributed 2–34% in winter and 1–4% in summer. In contrast to 1988, clupeids were unimportant in winter. Differences in diet composition appeared to reflect local changes in the availability of food, especially overwintering clupeids. Results indicate that dietary information obtained from short-term studies can be a poor indicator of subsequent diet composition and should be treated with caution when used to predict the effect of seals on prey populations.

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The size selectivity of whiting (Merlangius merlangus euxinus) caught by gillnet in the eastern Black Sea of Turkey

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s002531541400054x ◽

2014 ◽

Vol 94 (7) ◽

pp. 1539-1544

Author(s):

Ferhat Kalaycı ◽

Tuncay Yeşılçıçek

Keyword(s):

Black Sea ◽

Fish Species ◽

Sexual Maturity ◽

Mesh Size ◽

Size Selectivity ◽

Selectivity Curve ◽

Merlangius Merlangus

The size selectivity of traditional gillnets for whiting, (Merlangius merlangus euxinus) was investigated in the eastern Black Sea between June 2010 and June 2011. Experimental fishing operations were carried out by using gillnets of 16, 17, 18, 20 and 22 mm mesh size. A total of 2038 specimens belonging to 16 different fish species were caught during the experiment. The Share Each Length's Catch Total method was used to fit gillnet selectivity curves. Gillnet selectivity was best described by a bi-modal selectivity curve. The modal catch sizes were estimated as 14.81, 15.74, 16.66, 18.51 and 20.37 cm for 16, 17, 18, 20 and 22 mm mesh sizes, respectively. Modal lengths and spread values increased with increasing mesh size. The majority of fish (71.8%) caught by 16 mm mesh size were less than the length at first sexual maturity.

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Philometra barbata n. sp. (Nematoda: Philometridae) from the red mullet Mullus barbatus (Perciformes, Mullidae) off Tunisia

Acta Parasitologica ◽

10.1515/ap-2018-0091 ◽

2018 ◽

Vol 63 (4) ◽

pp. 766-771 ◽

Cited By ~ 1

Author(s):

Nessrine Ghanmi ◽

David González-Solís ◽

Lamia Gargouri

Keyword(s):

New Species ◽

Mediterranean Sea ◽

Body Length ◽

Nematode Species ◽

The Body ◽

Nominal Species ◽

Congeneric Species ◽

Red Mullet ◽

Mullus Barbatus ◽

The Family

Abstract Helminthological examinations of the red mullet Mullus barbatus (Linnaeus) (Mullidae) from the Gulf of Hammamet, off Tunisia, revealed the presence of one undescribed gonad-infecting nematode species, Philometra barbata n. sp. (Philometridae). The new species as other congeneric species is mainly characterized by the shape of the caudal mound, the distribution of the caudal papillae and the shape of the gubernaculum with the presence of a dorsal protuberance consisting of two dorsolateral lamellar parts separated from each other by a smooth median field in the male. The new species differs from its gonadinfecting congeners in the body length of male, the length of spicules and gubernaculum. This is the second nominal species of Philometra reported from fishes of the family Mullidae and the 14th from the Mediterranean Sea.

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