Circle Hooks in the Pacific

usually as hand-carved shell or CIRCLE HOOKS bone pendants on necklaces. A circle hook is defined as any IN THE PACIFIC round-shaped hook with a point that is perpendicular, or at a 90° angle, to the shank of the hook Circle hooks were probably first (Fig. 2). Figure 3 shows the parts used by Polynesian and Amer- Steve Beverly of a basic fish hook, including indian fishermen in the Pacific the point and the shank. It can SPC Fisheries hundreds or even thousands of be seen by comparison to a cir- Development Officer years ago.1 Now they are widely cle hook, that the hook in the used not only because they are ([email protected]) diagram — which is actually a good at catching fish, but also J hook — has the point parallel because they are “friendlier” to to the shank. Circle hooks are bycatch species in commercial is showing that circle hooks are sometimes called C hooks or G fisheries and catch-and-release able to maintain the same catch hooks because of their rounded species in recreational fisher- rates of target species so fisher- shape resembling those letters ies. In ancient times circle hooks ies that use circle hooks can re- of the alphabet. They are also were very well adapted to catch- main viable. often referred to as rotating, or ing small bottomfish from shore self-setting hooks. Circle hooks and from canoes using simple No one knows who invented the rotate in the direction of the handlines. In more recent times, circle hook but it was probably point when a fish takes the bait circle hooks are used as the developed by fishermen from and pulls on the line (Fig. 4). Be- hook of choice in commercial Oceania centuries ago. Circle cause of this rotating action, a and recreational fisheries. They hooks have been excavated from circle hook will set itself with no can be found almost anywhere archaeological sites in French action from the fisherman. The there are hook-and-line fisher- Polynesia, Hawaii (Fig. 1), and more the fish pulls, the deeper ies, and their popularity among in the Channel Islands off the the hook is set, even if the line fishermen, fisheries researchers, California coast where the Chu- is untended. No jigging is re- fisheries managers, and conser- mash Indians lived and fished. quired when using circle hooks. vationists is growing. Recent re- These ancient circle hooks were search has shown that the use of made from pearl and abalone Circle hooks were probably circle hooks in pelagic longline shell, bone (including human originally designed by fisher- fishing can mitigate bycatch and bone), and sometimes wood.1 men to catch small bottomfish. reduce mortality of non-target Replicas of these ancient Oce- In fact, circle hooks are pre- discarded species (Watson et anic hooks have become very ferred today by fishermen tar- al. 2005). More recent research popular as fashion accessories, geting deep-water bottom snap- pers. They are also used though for commercial tuna and swordfish fishing and for recreational catch-and-release fishing. Aside from their self-setting character- istic, circle hooks are less likely than J hooks to catch or injure bycatch species in commercial fisheries, and are less likely to injure either bycatch species or tag-and-release fish caught in recreational fisheries. Pelagic longline fishing targets tuna and billfish species such as bigeye tuna, yellowfin tuna, albacore tuna and broadbill Figure 1. Bone circle hook from the Hawaiian Islands. swordfish, but also catches non- target species. Some non-target 22 SPC Fisheries Newsletter #131 – January/April 2010 CIRCLE HOOKS IN THE PACIFIC Total length Shank Eye 90° Gape Bend Bite/throat Barb Point Front length Figure 2. Circle hook showing the point Figure 3. Hook anatomy (From Mustad website: at a 90° angle to the shank. www.mustad.no/abouthooks/index.php). Direction of pull Hook rotates Figure 5. Different size circle hooks used Figure 4. Circle hook showing in commercial and recreational fisheries direction of rotation when (not to scale — from Mustad website: the line is pulled. www.mustad.no/abouthooks/index.php). species are retained but others ic longlines are loggerheads and Recent experimental work in are discarded. These discarded leatherbacks, although olive rid- the Atlantic Ocean has shown species are called bycatch and ley and green turtles are caught that the use of 18/0 circle hooks include fish that have no com- as well. Turtles can be lightly (compared to J hooks) greatly mercial value and other species hooked in the mouth, deeply reduces sea turtle catch and, that are endangered and are pro- hooked (hook is swallowed), or in some cases, increases tar- tected by law, including sea tur- externally hooked on the neck or get catch (Watson et al. 2005). tles, seabirds, marine mammals flipper. Large tuna circle hooks Furthermore, when turtles are and sharks. Sea turtles that are have been shown to be useful in caught on circle hooks, injury caught as bycatch are of particu- mitigating the catch of sea turtles is reduced and turtles are more lar concern in pelagic longline in longline fisheries. Circle hooks likely to survive being caught fisheries because some turtle used in commercial and recrea- and released. Turtles caught on species are considered vulner- tional fisheries are made from circle hooks are less likely to be able to local and even global ex- high carbon galvanised steel or seriously injured because these tinction because of their declin- stainless steel, and range in size hooks are wide and are less ing numbers. The two species from 8/0 to 16/0 (Fig. 5) and likely to be swallowed. A recent caught most frequently on pelag- sometimes even 18/0. study using captive loggerhead SPC Fisheries Newsletter #131 – January/April 2010 23 CIRCLE HOOKS IN THE PACIFIC turtles showed that the overall mitigation technique or gear no input from the investiga- narrowest width of the hook is modification must not affect tors. Setting and hauling times, the most important measure- the commercial viability of the branchline length and material, ment because that is what de- fishery or else fishermen will number of hooks between floats, termines whether or not a turtle not be inclined to use them. Ex- setting depth, location and bait can swallow the baited hook periments are being carried out type are all determined by the (Watson et al. 2003). Mouth inju- in the Atlantic Ocean, the Medi- vessel operators. The investiga- ries compared with gut injuries terranean Sea, the Indian Ocean, tors monitor all sets to ensure are usually not fatal. The study and the Pacific Ocean, including that control and experimen- concluded that using hooks Hawaii and many small Pacific tal hooks are deployed evenly larger than 51 mm in width has Island countries and territories throughout each set and to the potential to significantly re- (PICTs), to show whether or not record all data. Data, including duce mortality of loggerhead the use of large circle hooks will fork length, are recorded using turtles incidentally captured on affect the commercial viability the SPC/Pacific Islands Forum longlines. A 16/0 circle hook, of pelagic longline fisheries. Fisheries Agency Regional Lon- for example, has a width of 51 gline Observer Catch Monitor- mm while a 9/0 J hook (which The Secretariat of the Pacific ing Form LL-4. Catch rates, or is similar in size to a 16/0 cir- Community (SPC) and Hawaii’s catch per unit of effort (CPUE), cle hook) has a width of only Pacific Island Fisheries Science are expressed as the number of 41 mm. Another recent study, Center (PIFSC) are currently fish caught per 1,000 hooks, or this time of recreational catch carrying out a series of experi- kilograms per 100 hooks. Ro- of bluefin tuna in the Atlantic ments using large circle hooks. bust data sets are being accu- Ocean, found that most of the The studies are taking place in mulated by monitoring at least fish caught on circle hooks were American Samoa, Cook Islands 65,000 experimental hooks in hooked in the jaw while J hooks and New Caledonia. The pur- approximately 45–50 longline were more often swallowed by pose of the experiments is to sets in each of the three fisheries the fish (Skomal et al. 2002). The compare the effectiveness of where the experiments are tak- estimated mortality for J hooks large (16/0) circle hooks with ing place. A statistical compari- in the study was seven times hooks normally used in Pa- son will be used to test the null greater than for circle hooks. cific Island domestic longline hypothesis of no difference in The study concluded that circle fisheries that target albacore CPUE for control hooks and ex- hooks cause less damage than tuna, bigeye tuna and broadbill perimental hooks at the conclu- J hooks and can be a valuable swordfish. The experiments are sion of the field trials, and sepa- conservation tool in recreational very simple, with only one in- rate reports will be submitted. tag-and-release fisheries. dependent variable, 16/0 circle The reports will assist regional hooks. The studies have been fisheries management organisa- Circle hooks have now become designed to compare catch rates tions in deciding whether or not mandatory in commercial lon- of the main target species using to mandate the use of large cir- gline fisheries in the United hooks normally used in the fish- cle hooks in their fisheries, and States that target swordfish, and ery (control hooks) with catch they will help to convince fish- may soon become mandatory rates using 16/0 circle hooks ermen of the efficacy of using for tuna longline fisheries as (experimental hooks).

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