No abstract

No abstract

In fisheries, the two morphological parameters of opercular and maximum girth are related to the effectivity of capture methods in gilled and wedged fish, respectively. The present work investigates the relationship between opercular (G ope ) and maximum girths (G max ) to total length (L t ) for 10 fish species captured from Shatt al-Arab River, Basrah, Iraq. Data were collected October 2005 to December 2006. Cyprinids were the best represented family with six species; engraulids, silurids, heteropneustids and mugilids were each represented by one species. G ope and G max were found to increase linearly with total length of all species, all r 2 values being greater than 0.73 and statistically significant (P < 0.01). When G ope and G max for all species were plotted against total length, two groups were identified (G1, G2), corresponding to general girth-length relationships: (a) G1 = )0.252 + 0.424 L t and G2 = )0.262 + 0.600 L t for opercular girth and, (b) G1 = 1.538 + 0.419 L t and G2 = 1.538 + 0.696 L t for maximum girth. These groups correspond to different body shapes of fishes: G1-round and G2-compressed. These relationships have implications when using length data and mesh size to determine size selectivity of gill nets.

Laboratory experiments were conducted to compare the growth performance and feed efficiency of two groups, old (H1) and new (H2) of common carp Cyprinus carpio L. (97.37+0.33 g). Fishes of the H1 introduced to Iraq in 1982 and then their reproduction and farming began on a large scale, while fishes of the H2 was introduced to Iraq in 2009 by Inmaa Agricultural Enterprises Organization. H2 group indicated significantly (p<0.05) better performance in several studied parameters which included specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), protein productive value (PPV), total apparent digestibility and apparent digestibility of protein and carbohydrates. This group also recorded significant (p<0.05) lower feed satiation level and fat deposited in the body compared to the old group (H1). Results of the current experiment concluded that there is a clear higher efficiency of the group H2 in most studied growth and feed efficiency parameters, which indicates the possibility of obtaining higher productivity and better economic profits when used in farming activities.

Berried females of Macrobrachium nipponense were incubated under four different temperatures (20,23,26 and 28 ºC) and two types of tanks with different background coloration (dark and transparent tanks) to determine the best larval release and the post larvae survival were observed. The results show best larval release were 124 ind./L achieved at 26 ºC at dark color tanks, while 68 ind. / L larvae were released at the transparent color tank at the same temperature, while only 16 ind./L were released from berried females incubated at 20 ºC at dark color tanks and 6 ind./L at the transparent tanks. The best survival of larvae was 80 % at 23 ºC at dark color tanks and 75 % at transparent color tanks. Four stages for eggs development were discriminated based on color, size and eyes.