Crocodile technology 609 на русском

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Nevertheless, there is scope for improvement, and options for utilization of the small quantities of fish currently discarded should be explored. Among the species and species groups taken as bycatch, almost all with the exception of noddies have been recorded before from tuna pole-and-line fisheries in both the Maldives see Introductionand the western Pacific [ 4344 ], and all are common and widespread.

In contrast, discards of small tunas have been a regular feature of western Indian Ocean purse seine fisheries. During this study, much of the non-retained bycatch was released alive, unlike many other fisheries in which most fish arrive on deck in poor condition or already dead e. In pole-and-line fishing, fish are brought on deck one at a time, and the flick-off de-hooking technique has very high survival rates [ 4378 ]. In the Maldivian pole-and-line fishery, the combination of barbless hooks, flick-off de-hooking and short time on deck is believed to promote similarly high survivorship.

It has been estimated that roughlytosilky sharks may be entangled and die annually in the netting of dFADs deployed by the purse seine fleet, a mortality 5 to 10 times higher than the reported catch [ 76 ]. There is also a problem for turtles, particularly olive ridley turtles Lepidochelys olivaceawhich frequently become entangled in FAD netting [ 7585 ].

While it is not surprising that whales, dolphins or turtles were not caught, the almost complete absence of discarded tuna is of note. In this study, only one skipjack and one yellowfin tuna were discarded, both depredated by sharks. Also during the course of Crocodile technology 609 на русском study, in interviews with 10 fishermen from 10 different boats, fishermen reported that they never discarded tunas because of size or damage; any tuna that could not be sold to processing plants would be retained for sale on local islands or for household consumption.

The ratio estimator method indicated, based on the total catch 85, t It is stressed that these estimates are very crude and unlikely to be robust, as the sample size just days fishing is relatively small, and there are insufficient data to warrant stratification by school type, region or season. However, the issue of waste, which is a major issue in many fisheries, is shown to be of minor concern for the case of the Maldives pole-and-line fishery.

The bycatch rate recorded here 0. In a review of the limited and scattered literature, average bycatch was estimated at 0. Observer data from the Solomon Islands gave an estimated bycatch of 0. In a global review, a mean discard rate of 0. By most standards the bycatch rate reported here, and in other tuna pole-and-line fisheries, is low. The discard rate reported here is particularly low. While extrapolation of such a small sample to the entire fishery has very low confidence, it gives a first indication of the likely scale of these bycatch categories.

However, they have been poorly documented. Most of the bycatch sampling Crocodile technology 609 на русском date has been of landings, not catches, so discards are unknown. If that were representative of all Indian Ocean tuna gillnet fisheries, then it would suggest bycatch in excess oft in It should be noted, however, that a large part of the bycatch is of other edible finfish and of sharks, most of which are sold as byproduct. The tuna purse seine fishery in the Indian Ocean is dominated by French and Spanish fleets.

Because most of the bycatch is used for human consumption, discards from this fishery are particularly low. Nevertheless, there may be some scope to encourage further utilization of some of the very small quantity of low-value fish that is currently discarded, and to further reduce and mitigate the small number of interactions with sharks and seabirds.

Furthermore, the skipjack caught from free schools were mostly uniformly large-sized, whereas smaller skipjack predominated in associated-school catches Fig 2A and S5 Table. Across the entire study, skipjack lengths showed a bimodal distribution Fig 2A ; this is a well-known feature of Maldivian skipjack landings [ 5758 ]. Also, across the entire study, skipjack contributed The yellowfin tuna taken by pole-and-line were all juveniles, with an Crocodile technology 609 на русском fork length of roughly 40 cm in both free schools and associated schools Fig 2BS5 Table.

While no entanglements were observed during this study, there are infrequent anecdotal reports of entangled turtles. Bycatch management for large industrial fisheries e. Therefore, rather than trying to reduce bycatch rates, management efforts should concentrate on reducing impacts on ETP species [ 4 ]. For the Maldivian pole-and-line fishery, interactions with ETP species are already limited, but assessing and mitigating impacts on silky sharks and birds should be a priority.

Both of these bird species are common in the Maldives and the wider region, and the conservation status of both has been assessed as Least Concern [ 45 ]. Maldivian fishermen frequently use the presence of seabirds to locate tuna schools [ 48 — 51 ]. All three noddies were apparently uninjured, and flew away strongly on release, although the possibility of sublethal impacts, or post-release mortality, cannot be entirely dismissed. It would be inappropriate to multiply up from such a small sample, so the total number of seabirds being hooked in this fishery is unknown.

There is also a need to ensure that all Maldivian aFADs are non-entangling.

This is comparable to, but slightly more efficient than, catch rates estimated by previous Maldives studies summarised in [ 36 Crocodile technology 609 на русскомwhich reported catches Crocodile technology 609 на русском the range of 7.

In contrast, associated schools contained mostly smaller-sized skipjack together with juvenile yellowfin and bigeye tunas, and yielded much more bycatch. Similar differences in tuna composition and bycatch rates between free schools and FAD schools are known from the purse seine tuna fisheries e.

However, on a regional scale it might be more useful to increase the monitoring of other fisheries notably pelagic gillnetting which have more significant bycatch issues. This was due to the fact that the Maldivian pole-and-line fishermen did not perceive that they were in any way doing anything untoward: they had nothing to hide. This attitude might change in the future if legal restrictions were introduced. In summary, this study confirms previous suggestions that bycatch and discards in the Maldivian pole-and-line tuna fishery are low.

Bycatch from the north included more rainbow runners and round scad, while dolphinfish dominated in the south. Among tunas, Crocodile technology 609 на русском was relatively more abundant in the south of Maldives, while kawakawa and frigate tuna were relatively more abundant in the north. Differences in relative abundance of different pelagic fish species between these regions have been attributed to differences in oceanographic Crocodile technology 609 на русском [ 56 ].

The most important factor influencing bycatch rate was tuna school association. Free schools Crocodile technology 609 на русском typically composed almost entirely of large skipjack, and yielded little bycatch.

While this report deals specifically with bycatch, some information Crocodile technology 609 на русском the tuna catch is relevant to interpreting the bycatch data. Different school types showed markedly different tuna species composition and different sizes of skipjack tunas Table 2 and Fig 2A.

None are considered endangered [ 45 ]. The one species for which there is some concern is the silky Crocodile technology 609 на русском, which has been assessed as Near Threatened [ 45 ] and is known to have declined in abundance in Maldivian waters and in the wider Indian Ocean [ 646 Crocodile technology 609 на русском.

The Maldives initiated a proposal to CITES the Convention on International Trade in Endangered Species of Wild Fauna and Flora CoP17 for silky shark to be listed in its Appendix II, which passed in During this study, three seabirds one lesser noddy and two brown noddies were caught, but all were released and flew away apparently unharmed.

The issue of bait. In this study, as in most similar studies, the livebait component of the pole-and-line fishery was not considered bycatch due to different target species, different gears, different locations, Crocodile technology 609 на русском different management issues. For these reasons the catch of livebait is usually excluded from the definition of bycatch [ 13141544 ]. One exception to this standard practice was provided by [ 25 ], wherein livebait was Crocodile technology 609 на русском in bycatch estimates for the Maldivian pole-and-line fishery and, based on published information from MRC, noted bycatch at For comparison with [ 25 ], during this study it was estimated that total livebait catch was That was equivalent to 8.

For these fleets, bycatch was sampled during — by onboard observers, and estimated at 11, t per year, which was 4. This likely underestimated total bycatch, since marine mammals and whale sharks were caught but excluded from the analysis, and rare catches of large numbers of some bycatch species were under-represented in Crocodile technology 609 на русском observer samples [ 69 ].

Comparisons between non-entangling and entangling FADs suggest equal tuna attraction, while reducing tangling mortality of other marine life [ 8687 ]. IOTC has adopted a resolution to phase out entangling FADs, but progress appears to be slow. The ecological impacts of these two types of FAD must therefore be very different, especially as aFADs tend to have smaller net panels than dFADs [ 88 ].

Indeed, purse seine bycatch ranged from a low of 0. For the Maldivian pole-and-line fishery there may be differences between different types of associated schools, but the quantities of bycatch taken from the different school types during this study are too small to make meaningful comparisons. Within the Maldives there are clear regional differences in bycatch composition. There were also differences in species composition.

Indeed, bigeye catches were generally not separated from yellowfin catches in official Maldivian catch statistics untilwhen bigeye catches began being recorded separately in the logbooks. In this study, the proportion of bigeye in the Thunnus component of the pole-and-line catch was estimated at 6. This agrees with previous studies [ 61 — 63 ], which all found a higher proportion of bigeye in the south of Maldives than in the north and centre S7 Table. The cause of this latitudinal variation in bigeye tuna abundance is unknown, but may be related to a known deep oxygen minimum zone [ 6566 ] that could affect deep-swimming species such as bigeye.

Seabird catches are typically minimal in pole-and-line fisheries, although 3 were caught during the course of this study. A review of Pacific pole-and-line bycatch found no records of seabird captures [ 43 ]. In a study of the Brazilian skipjack pole-and-line fishery, no seabird captures were reported, although fishermen did deliberately hit seabirds to scare them away [ 80 ]. In contrast, in the southern Indian Ocean, tuna longline fisheries have been a major source of mortality for several species of seabirds, particularly petrels and albatrosses e.

A precautionary approach to its management has been recommended by the IOTC Scientific Committee [ Crocodile technology 609 на русском ]. All forms of shark fishing were banned in the Maldives from March [ 28 ]. There is scope for further education of fishermen on the protected status of sharks, and on techniques for reducing bycatch and facilitating safe release if hooked.

Most FADs both anchored and drifting are deployed with swathes of netting underneath, which are believed to increase their aggregating power, but can lead to animal entanglement and death. In the western Indian Ocean purse seine fisheries, very high numbers of dFADs are employed: more than 7, dFADs were estimated to have been deployed in the Indian Ocean in [ 83 ], and 6, active dFADs were deployed by the French and Spanish purse seine fleets in the western Indian Ocean at the end of [ 84 ].

As noted above, the Maldivian pole-and-line fishery makes full use of the network of approximately 50 aFADs deployed around the atolls [ 8182 ]. Crocodile technology 609 на русском network of aFADs was developed by the Government of Maldives to provide an opportunity for fishermen to locate and catch tuna with a relatively high likelihood of success, and it has worked, with roughly one third to one half of the total tuna catch now coming from aFADs [ 39 ], present study.

Nevertheless this is an issue that deserves further study. At the same time there is scope for futher education of fishermen on the importance of seabirds to the fishery, their protected status, and techniques to avoid capture and to facilite safe release if hooked. Variation Crocodile technology 609 на русском bycatch rates. The results of this study demonstrate that Crocodile technology 609 на русском is considerable variability in bycatch rates.

Nevertheless, there is scope for improvement. Maldivian aFADs are deployed with netting attached underneath, and Maldivian fishermen do sometime add extra lengths of netting to aFADs pers.

One useful line of research would be electronic tagging of released animals to provide confirmation of survival rates, as has been done in the purse seine fishery [ 79 ]. The days fishing observed during this study were sufficient to provide a first estimate of bycatch rates for major bycatch species, as intended. However, it is inevitable that with such a small sample size, some rare interactions with ETP species must have been missed by this study.

Thus, there is considerable variation in tuna catch and bycatch, and bycatch rates can be particularly high in some tuna longline fisheries.

There is very little gear loss and effectively no ghost fishing from the pole-and-line fishery. One of the more striking aspects of the pole-and-line bycatch recorded here is not what was included in the bycatch, but what was not present.

For example, seabird bycatch has been unsustainably high in the southern Indian Ocean e. With such variability, it is difficult to make a robust estimate of total bycatch. However, a large study of bycatch on Taiwanese tuna longliners which covered much of the Indian Ocean found that bycatch and discards comprised If this were representative of all Indian Ocean tuna longline fisheries, then it would suggest bycatch of the order oft in While there is much uncertainty in these bycatch estimates, it is clear that other tuna fisheries, particularly gillnet and longline fisheries, have much higher bycatches than the Crocodile technology 609 на русском pole-and-line fishery.

And for all of these other fisheries, there is also the problem of ghost fishing gear: lost or discarded pieces of fishing gear which may continue to catch a wide variety of species for months or years [ 7475 ]. Within the Indian Ocean, ghost gillnets and purse seine FADs have been implicated in the mortality of particularly large numbers of silky sharks and olive ridley turtles, Lepidochelys olivacea [ 7576 ]. Such mortalities should be considered as part of the bycatch of the gillnet and purse seine fisheries.

This was partly because the main southern fish buyers would only buy skipjack, yellowfin and bigeye, while northern buyers would buy other species as well. These factors may have encouraged northern fishermen to take more bycatch. It is likely that there are also seasonal differences in bycatch. However, these are not apparent in our data, in part perhaps because of the relatively small sample sizes.

In addition, the proportion of dFAD-sets by tuna purse seiners has been increasing in recent years [ 70 ], which has likely resulted in the proportion of bycatch increasing. Longline tuna fisheries cover all tropical and temperate waters of the Indian Ocean. Although the basic longline technique is fairly standard, there is much variation Crocodile technology 609 на русском gear materials and configuration, in setting depth and between ecological regions.

It should be noted that Maldivian pole-and-line fishermen can clearly see what they are catching, and will not continue catching species which they cannot sell or consume. During this survey it was apparent that there was greater demand for bycatch species in the north of Maldives than in the south.

This agrees with previous findings [ 60 ]. Juvenile bigeye tuna makes up a small proportion of the Maldivian pole-and-line catch Table 2but these fish are not always easy to distinguish from juvenile yellowfin tuna.

Comparison with other fisheries. In comparison to other fisheries, a bycatch rate of 0. Worldwide, total pole-and-line fishing discards were estimated at 3, t, compared witht for tuna purse seine in [ 15 ]. Within the Indian Ocean, in addition to pole-and-line, the other major tuna fishing gears are gillnet, purse seine and longline.

Gillnet fisheries are not only the largest tuna fisheries in Crocodile technology 609 на русском Indian Ocean but are also believed to have the highest levels of bycatch.