MARTIN THIEL ET AL.Niño 3.4 index3210−1−2−3L<strong>and</strong>ings (1000 t)2.5002.0001.5001.00050004.5003.5002.5001.5005000350250150CHUB MACKERELANCHOVYJACK MACKEREL5003.0002.000PACIFIC SARDINE1.0000800600400200COMMON SARDINE01982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004Figure 27 Total annual l<strong>and</strong>ings for <strong>the</strong> five most important pelagic species caught by <strong>the</strong> Chilean purse seinefleet during <strong>the</strong> time period 1980–2005 in <strong>the</strong> respective fisheries units; grey dots represent Fisheries Unit I–II,open dots Fisheries Unit III–IV, grey triangles Fisheries Unit V–IX, <strong>and</strong> open triangles Fisheries Unit X–XII.Yáñez et al. (1996) conducted a survey to assess <strong>the</strong> possibility <strong>of</strong> introducing <strong>the</strong> use <strong>of</strong> SST,obtained from NOAA (National Oceanic & Atmospheric Administration) satellite data, for <strong>the</strong> smallpelagic fisheries resources <strong>and</strong> found significant relationships between species yields <strong>and</strong> TGRs.Jack mackerel yields were largely related to strong TGRs next to oceanic waters, while anchovy<strong>and</strong> common sardine yields were mainly associated with <strong>the</strong> development <strong>of</strong> coastal upwellingevents. Comparison with <strong>the</strong> SST anomalies shows that l<strong>and</strong>ings <strong>of</strong> anchovy negatively correlate290
THE HUMBOLDT CURRENT SYSTEM OF NORTHERN AND CENTRAL CHILEwith SST anomalies (Yáñez et al. 2001); also chub mackerel l<strong>and</strong>ings seem to correlate with SST(Figure 27). In contrast, interannual variations in <strong>the</strong> l<strong>and</strong>ings <strong>of</strong> <strong>the</strong> o<strong>the</strong>r three species seem tobe largely independent <strong>of</strong> variations in SST (Figure 27). The stabilisation <strong>of</strong> maximum anchovyl<strong>and</strong>ings between 1.5 <strong>and</strong> 2.7 million t during <strong>the</strong> 1990s <strong>and</strong> <strong>the</strong> parallel decline <strong>of</strong> <strong>the</strong> l<strong>and</strong>ings<strong>of</strong> <strong>the</strong> Pacific sardine in <strong>the</strong> HCS (<strong>and</strong> <strong>the</strong> entire sou<strong>the</strong>astern Pacific) reflects ano<strong>the</strong>r regime shiftfrom <strong>the</strong> warm ‘sardine regime’ to a cool ‘anchovy regime’ (Chavez et al. 2003, Alheit & Niquen2004, Halpin et al. 2004). These regime shifts occur on multidecadal scales <strong>and</strong> are probably relatedto <strong>the</strong> PDO, but <strong>the</strong> mechanisms driving <strong>the</strong>se changes are not yet well understood.Silva et al. (2003) studied <strong>the</strong> relationship between chl-a concentration, SST, <strong>and</strong> fishing yields<strong>of</strong> anchovy, Pacific sardine <strong>and</strong> jack mackerel in nor<strong>the</strong>rn Chile during summer <strong>and</strong> autumn 1999.CPUE superimposed over SST images confirmed that <strong>the</strong> anchovy has a more coastal distributionthan Pacific sardine <strong>and</strong> jack mackerel, being found in <strong>the</strong> frontal zone <strong>of</strong> coastal areas. In <strong>the</strong>sou<strong>the</strong>astern Pacific, <strong>the</strong> jack mackerel is a heavily exploited pelagic species, <strong>and</strong> its presence in<strong>the</strong> HCS in autumn <strong>and</strong> winter is assumed to be mainly due to an inshore feeding migration(Bertr<strong>and</strong> et al. 2004). During warmer years, jack mackerel may immigrate into coastal waterswhere <strong>the</strong>y are thought to exert high predation pressure on anchovy (Alheit & Niquen 2004).Changes in SST associated with EN events may also affect <strong>the</strong> migration pattern <strong>of</strong> jack mackerel,which needs to be taken into account in stock assessment <strong>and</strong> management plans (Arcos et al. 2001).Management <strong>of</strong> pelagic fisheriesAccording to Aguilar et al. (2000) <strong>the</strong> traditional method used to conserve fish stocks <strong>and</strong> preventoverfishing is to set a TAC for <strong>the</strong> fishery. Typically, TACs aim to restrict fishing effort to its MSY(maximum sustainable yield) level. Once <strong>the</strong>se ‘safe biological limits’ are reached, fishing isprohibited. But TACs do not, by <strong>the</strong>mselves, address <strong>the</strong> overcapitalisation issue. Consequently,many fisheries economists recommend that <strong>the</strong> designated TAC is distributed to industry participantsin <strong>the</strong> form <strong>of</strong> individual transferable quotas (ITQs), quasi property rights that restrict additionalaccess to <strong>the</strong> fishery. Under <strong>the</strong>se rules, failure to acquire an ITQ effectively forces vessels out <strong>of</strong><strong>the</strong> fishery, <strong>the</strong>reby reducing fishing effort <strong>and</strong> increasing harvesting efficiency.The Chilean General Law <strong>of</strong> Fisheries <strong>and</strong> Aquaculture considers three types <strong>of</strong> access to <strong>the</strong>fishery: (1) Full Exploitation Regime, which includes setting an annual quota or TAC by fishingunit, which can be temporally divided during <strong>the</strong> year <strong>and</strong> also modified once during that sameperiod (once <strong>the</strong> full exploitation regime is assigned to a given species no more fishing vessels areallowed to enter <strong>the</strong> fishery); (2) Recovering Fishery Regime is <strong>the</strong> fishery under a state <strong>of</strong>overexploitation, subject to a capture ban <strong>of</strong> at least 3 yr, to obtain its recovery <strong>and</strong> where an annualquota (or TAC) can be established; <strong>and</strong> (3) Early Developing Fishery Regime, which is a demersalor benthonic fishery with open access where an annual quota can be established <strong>and</strong> where n<strong>of</strong>ishing effort is applied or if it is done it is less than 10% <strong>of</strong> this quota.In 1993 <strong>the</strong> first pelagic fisheries in Fisheries Unit I–II were assigned <strong>the</strong> status <strong>of</strong> FullExploitation Regime, <strong>and</strong> by 2000 this had extended to four <strong>of</strong> <strong>the</strong> five fisheries (anchovy, jackmackerel, Pacific sardine <strong>and</strong> common sardine) <strong>and</strong> to all fisheries units. The chub mackerel is one<strong>of</strong> <strong>the</strong> few commercial species that is still under ‘open access’, with no regulation to date.Alternative management tools have been developed <strong>and</strong> used in <strong>the</strong> last years: in 1998, <strong>the</strong> use<strong>of</strong> a geographical positioning <strong>system</strong> for <strong>the</strong> industrial <strong>and</strong> artisanal fleets was established; later in2001 <strong>the</strong> Límite Máximo de Captura por Armador (LMCA, maximum capture limit per owner)was introduced for <strong>the</strong> industrial fleet in <strong>the</strong> fisheries for <strong>the</strong> small pelagics anchovy, sardines <strong>and</strong>jack mackerel in all fishery units, which is essentially an ITQ, <strong>and</strong> at least had <strong>the</strong> effect <strong>of</strong> reducing<strong>the</strong> fishing fleet. The LMCAs are determined using captures (1997–2001) <strong>and</strong> corrected holdcapacity (authorised hold capacity in cubic metres times authorised area length divided by total291