Kocabas M; Bascinar N

Research Article

Austin Biol. 2016; 1(3): 1015.

Assessing Stock Reproductive Potential of Salmorizeensis, Salmo trutta abanticus, Salmo trutta caspius, Salmo trutta fario and Salmocoruhensis with Fecundity

Kocabas M¹* and Bascinar N²

²Department of Wildlife and Fisheries, Karadeniz Technical University, Turkey

^¹Department of Fisheries Technology Engineering, Karadeniz Technical University, Turkey

*Corresponding author: Kocabas M, Faculty of Forestry, Department of Wildlife and Fisheries, Karadeniz Technical University, 61080 Trabzon, Turkey

Received: October 04, 2016; Accepted: November 16, 2016; Published: November 18, 2016

Abstract

Determination of the annual total egg production of a stock is important due to understanding fluctuations in population size. Therefore, the objective of the present work was to assess and compare the fecundity of Salmorizeensis, Salmo trutta abanticus, Salmo trutta caspius, Salmo trutta fario and Salmocoruhensis. Sampling was carried out by electro fishing. The results showed that the highest individual fecundity was in S. Coruhensis (1476±1043) while the highest relative fecundity was in S. t. caspius (4000±1092) (p<0.05). Egg sizes and weights of S. t. abanticus, S. rizeensis, S. t. caspius, S. t. fario and S. coruhensis were 4.91±0.37 mm and 92.21±16.07 mg; 4.52±0.53 mm and 59.42±12.32 mg; 4.23±0.26 mm and 48.92±5.32 mg; 4.59±0.53 mm and 81.54±21.41 mg, and 4.67±0.46 mm and 76.52±17.52 mg, respectively. The relationships between egg size and egg weight of S. trutta subspecies were found significantly (p<0.05). The results also showed that fecundity significantly increased with fish weight and length (p<0.05). Overall fecundity and egg size is affected by fish size and species.

Keywords: Fecundity; Salmorizeensis; Salmo trutta abanticus; Salmo trutta caspius; Salmo trutta fario; Salmocoruhensis

Introduction

S. trutta is one of the most important fish species due to its aquaculture potential, economic value and wide consumer demand and S. trutta forms resident populations in the upper streams of rivers and occurs in North Africa, Europe, West Asia and Anatolia and is characterized by extensive genetic, morphological and ecological diversity [1,2]. Thus far, based mainly on morphological data, the numerous forms of brown trout S. trutta have been classified under different taxonomic groupings [3]. S. trutta is represented by five subspecies within the Turkey; Salmo trutta macrostigma, Salmo trutta labrax, Salmo trutta caspius, Salmo trutta fario and Salmo trutta abanticus. Recently, S. t. labrax and S. t. macrostigma was described by Turan et al. [4] as Salmocoruhensis and Salmorizeensis, respectively [5,6].

Fecundity is expressed as one of reproductive traits [7] and it is an important biological parameter for successful fisheries management, to evaluate the commercial potentialities of a fish stock and plan a breeding programme [8]. Estimation of fecundity is essential to assessment the reproductive potential of a stock, fluctuations in reproductive output and population growth rate [8-11]. In addition, a better understanding of reproductive development and associated fecundity is necessary for culture studies. To date, reproduction biology and ecology of S. trutta has been intensively studied [3,12- 23], but fecundity pattern of subspecies of S. trutta was not compared. Therefore, this study was designed to investigate to compare of fecundity of S. rizeensis, S. t. abanticus, S. t. caspius, S. t. fario and S. coruhensis inhabiting North Anatolia Rivers, Turkey.

Materials and Methods

Sampling of wild fish

A total of 168 individuals caught from sampling sites in North Anatolia rivers (S. coruhensis, Camlihemsin-Firtina Stream; S. t. fario, Camlihemsin-Firtina Stream-Meryemana Stream; S. rizeensis, Caykara-Ipsil-Yedigoller Lake; S. t. abanticus, Yedigoller Lake; S. t. caspius, Susuz-Cildir Lake) in Turkey, using by electro fishing (SAMUS 725G, 650 W, 5-60 A and 12 V DC). After cessation of oviposition, post-spawning females were removed, anaesthetized with Benzocaine (ethyl 4-aminobenzoate), weighed and measured. Fish were allowed to recover fully before being returned. Total weight, weight of gonads and its subsamples were recorded with an electronic analytical balance to the nearest 0.01 g.

Estimation of fecundity

The number of eggs was estimated by gravimetric method, using three pieces removed from the ovary. They were then counted and mean value calculated from three sub-samples and weighed. The total number of eggs in each sub-sample ovary was determined. This value was proportional to the total ovary weight; the number of eggs (F1) for the subsample was estimated using the equation, F1= (Gonad weight x number of eggs in the subsample)/subsample weight. Then, by taking the mean number of three subsample fecundities (F1, F2, F3), the individual fecundity for each female fish was calculated [F= (F1 + F2 + F3)/3]. Relative fecundity index was calculated as RF = AF/TW, where AF is individual fecundity and TW total weight [24].

Fork length, fecundity and body weight, and fecundity relationships were determined from the equations; F = q x FL^b and F = q x W^b_B, where F is the number of eggs (fecundity), FL and W_B are the fork length (mm) and body weight (g), respectively. “a” and “b” are constant parameters in linear regression analysis and q = e^a. Fecundity was estimated according to Bagenal and Braum [25]. The egg shapes were round and slightly hard when diameters were being measured. The mean fecundities and mean egg diameters for individuals were recorded by length and weight of each examined female fish.

Statistical analysis

The differences in between groups were tested with the one-way ANOVA test and Tukey test. Statistical analyses were performed with SPSS 14.0 software package and significant levels of 0.05, 0.01 and 0.001 were accepted. Relationship between fecundity and length, weight, and also between egg size and egg weight was described by exponential and linear equations: F= abL; F= abt and F = a + bW.

Results

Mean length (cm) and weight (g) values of female S. rizeensis, S. abanticus, S. t. caspius, S. t. fario and S. coruhensis during spawning period are presented in Table 1. Significant differences were obtained from the statistical comparison of length-weight relationships among subspecies (p<0.05).

Table 1: Mean length (cm) and weight (g) values of female S. t. abanticus, S. rizeensis, S. t. caspius, S. t. fario and S. coruhensis.




  
     
    n
    Length (min-max) (cm)
    Weight (min-max) (g)
  
  
    S. t.    abanticus 
    23
    31.45±8.54^b (15.6-43.0)
    482.02±360.44^b (41.3-1250.0)
  
  
    S. rizeensis 
    22
    19.54±4.44^a (13.6-29.3)
    82.51±61.20^a (28.3-298.0)
  
  
    S. t.    caspius 
    20
    21.25±2.05^a (18.1-24.5)
    123.38±24.83^a (87.4-155.0)
  
  
    S. t. fario 
    27
    34.47±9.30^c (26.0-50.8)
    628.56±358.50^c (228.0-2150.0)
  
  
    S.    coruhensis 
    73
    35.15±7.95^c (22.0-54.9)
    647.81±502.00^c (140.0-2410.0)
  
  
    ^a,b,c Different superscripts within the same column demonstrate    significant differences.
      (p<0.05)



Table 1:  Mean length (cm) and weight (g) values of female S. t. abanticus, S.
rizeensis, S. t. caspius, S. t. fario and S. coruhensis.

The relationship of some features [total egg mass (g), egg weight (mg), egg diameter (mm), individual fecundity (egg/individual), relative fecundity] with five ecotypes of brown trout are shown in Table 2. Egg sizes and weights of S. t. abanticus, S. rizeensis, S. t. caspius, S. t. fario and S. Coruhensis were 4.91±0.37 mm and 92.21±16.07 mg; 4.52±0.53 mm and 59.42±12.32 mg; 4.23±0.26 mm and 48.92±5.32 mg; 4.59±0.53 mm and 81.54±21.41 mg, and 4.67±0.46 mm and 76.52±17.52 mg, respectively. It was determined that the biggest egg was in S. t. abanticus and the smallest was S. t.

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Citation: Kocabas M and Bascinar N. Assessing Stock Reproductive Potential of Salmorizeensis, Salmo trutta abanticus, Salmo trutta caspius, Salmo trutta fario and Salmocoruhensis with Fecundity. Austin Biol. 2016; 1(3): 1015.

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	*S. t. abanticus*	*S. rizeensis*	*S. t. caspius*	*S. t. fario*	*S. coruhensis*
*TEW*	60.13±56.86^ab	11.78±7.87^a	24.81±10.06^a	106.20±102.31^bc	112.02±92.02^c
EW	92.21±16.07^a	59.42±12.32^c	48.92±5.32^c	81.54±21.41^ab	76.52±17.52^b
ED	4.91±0.36^a	4.52±0.53^bc	4.23±0.26^c	4.59±0.53^abc	4.67±0.46^ab
IF	623±515^bc	193 ±123^c	505 ±206^bc	1179±669^ab	1476 ±1043^a
RF	1871±742^b	2403±953^b	4000±1092^a	1988±865^b	2314±858^b
^a,b,cDifferent superscripts within the same raw demonstrate significant differences. (p<0.05)

	Model	a	b	r²	F
Length (x) - Fecundity (y)
*S. t.abanticus*	y = a x ^b	0.0706***	2.627095***	0.941	271.57
*S. t.caspius*	y = a x ^b	0.0107*	3.505514**	0.665	19.81
*S. t.fario*	y = a x ^b	1.8657 n.s.	1.784433***	0.712	54.38
*S.coruhensis*	y = a x ^b	0.0463**	2.846369***	0.673	125.34
*S. rizeensis*	y = a x ^b	0.3189 n.s.	2.082436***	0.629	28.87
Total Weight (x) - Fecundity (y)
*S. t.abanticus*	y = a + b x	71.100 n.s.	1.344700***	0.884	130.11
*S. t.caspius*	y = a + b x	-304.396 n.s.	6.563795**	0.628	16.89
*S. t. fario*	y = a + b x	541.336***	0.792415***	0.690	55.70
*S.coruhensis*	y = a + b x	293.476*	1.767080***	0.713	151.80
*S. rizeensis*	y = a + b x	48.904*	1.792892***	0.755	46.34
Egg size (x) - Egg weight (y)
*S. t.abanticus*	y = a + b x	-0.07456*	0.033728***	0.791	41.67
*S. t.caspius*	y = a + b x	-0.02687*	0.017924***	0.791	37.86
*S. t. fario*	y = a + b x	-0.09197***	0.037342***	0.882	165.23
*S.coruhensis*	y = a + b x	-0.07746***	0.032908***	0.798	246.06
*S. rizeensis*	y = a + b x	-0.03987**	0.023369***	0.740	57.06
: p<0.05 *: p<0.01 `