This paper describes the weight–length relationships (WLRs) and Fulton’s condition factors (K) of skipjack tuna (Katsuwonus pelamis) in purse seine fisheries from three cruises in the western and central Pacific Ocean (WCPO): (ND12), and (JJ13). The fork length and weight of a total of 1678 specimens were measured. The results showed that the fork length of more than 70% of specimens was below 60 cm (76% in AS09, 87% in ND12, and 73% in JJ13). The coefficient b in the combined sex group was 3.367, 3.300 and 3.234 in JJ13, AS09 and ND12, respectively. The b values of WLRs when fork length was >60 cm were significantly less than 3 (P = 0.062), but when fork length was <60 cm they were significantly greater than 3 (P = 0.028). The K value ranges of JJ13, AS09 and ND12 in different fork length groups were 1.3–1.84 (1.62 ± 0.18), 1.57–2.02 (1.86 ± 0.15), and 1.44–1.78 (0.65 ± 0.13), respectively. Moreover, K values in different fork length classes for each cruise had one turning point: 60–65 cm for JJ13; 60–65 cm for ND12; and 55–60 cm for AS09. The results of this study provide basic information on the WLRs and K values of skipjack tuna in different seasons and growth phases in the WCPO, which are useful for fishery biologists and fishery managers.
Inclusion
Skipjack tuna (Katsuwonus pelamis) are good pelagic, highest efficiency species with an optimum age less than cuatro.five years (Fromentin Fonteneau, 2001). Because an essential commercial species, it’s mostly trapped inside exotic and subtropical oceans of one’s Pacific, Atlantic, and you can Indian seas. Captures of skipjack tuna comprise more than migliore donna thai 70% of the many tuna catches throughout the western and you can central Pacific Water (WCPO), in which half of the fresh world’s tuna are caught (As well as Farming Team of your United nations, 2011). From the WCPO, 86% of skipjack tuna are c). Throughout fishery facts, some elementary physical variables (age.g., proportions, weight) are necessary for comparing fishery sustainability also to evaluate stocks (Fromentin Fonteneau, 2001; Hampton, 2000).
Weight–duration relationship and you may Fulton’s reputation items from skipjack tuna (Katsuwonus pelamis) regarding west and you can main Pacific Ocean
The weight–duration relationship (WLR) and you will Fulton’s standing basis (K) are two head parameters included in fishery browse, and get come directly associated because they were first suggested (Froese, 2006). The fresh new WRL ‘s the relationship anywhere between pounds and you may duration to own an excellent provided varieties, and will be employed to imagine the development pattern. Earlier research has sensed the fresh new WLRs out-of skipjack tuna about CPWO (Wild Hampton, 1993; Sunlight Yeh, 2002; Sunrays ainsi que al., 2003; Froese Pauly, 2014); but not, they generally dedicated to the brand new WLR of all of the skipjack tuna specimens stuck. Ergo, everything covered by more many years/body kinds wasn’t certainly understood. Furthermore, predicated on a recently available WCPO skipjack tuna status report (Harley mais aussi al., 2011), short fish (40–sixty cm; 1–24 months) ruled catches, but inside the 2005. not, nothing happens to be identified regarding differences when considering physical parameters during more increases levels. Confusion eters of your own WLR) were used to compare the difference among the some other levels of just one observation, as well as other for the situ observations; specifically, just like the a stages make a difference b philosophy, and better b philosophy was with the less a degree (Froese, 2006). The worth of K is actually determined throughout the pounds and you can length, and certainly will be used to estimate alterations in nutritional standing. Pair training in recent times keeps examined new K really worth having skipjack tuna. Earlier in the day research has shown that K viewpoints with other seafood alter seasonally (come across Froese, 2006 and you will recommendations therein) with gains phase. Skipjack tuna are recognized to end up being firmly impacted by macro-aquatic requirements, elizabeth.grams., Este Nino and Los angeles Nina (Lehodey mais aussi al., 1997; Lehodey ainsi que al., 2013; Loukos et al., 2003); although not, a similar changes as with most other fish types just weren’t reported having skipjack tuna. Even if both the WLR and you will K can echo the organization criteria away from particular fish, zero studies that blend analysis of the two indices were stated. Thus, it stays uncertain whether or not they has actually uniform trend that reflect the fresh new society qualities from skipjack tuna throughout the WCPO.