El Niño Southern Oscillation and tuna in the western Pacific

“…and abundance of tuna (particularly bluefin, Thunnus thynnus) larvae, and the migratory patterns and seasonal availability of skipjack and bigeye (T. obesus) tunas, have changed in concert with a 3–4 C temperature increase and other environmental changes (Lehodey et al., 1997; ICCAT, 2002).”

“Numerous studies have demonstrated a strong link between climatic fluctuations, such as El Niño and La Niña events, and the distribution or productivity of exploited fish populations (Lehodey et al. 1997; O’Brien et al. 2000; Worm et al. 2005; Ottersen et al. 2006).”

“Assessments The distributions and abundances of the four main species of tuna in the tropical Pacific (skipjack, yellowfin, bigeye and albacore), and the way they vary with the El Niño Southern Oscillation (ENSO) [35], are increasingly well understood [36,37].”

“…1, about here The spatial distribution and movement of ABFT are hypothesized to be controlled by preferential ranges and gradients of temperature (see e.g., Roffer 1987), similar to Pacific bluefin and other tuna species (Laurs et al. 1984; Lehodey et al. 1997; Bard 2001; Inagake et al. 2001).”

“And finally, some climate-based decisions are tied directly to these oceanic observations, such as for the fishery industry (Lehodey et al., 1997; Carr and Broad, 2000), in which case high resolution, accurate, and current observations are crucial (GOOS, 1998).”

“Oceanographic regime shifts have been identified as important drivers of fish production in many regions, including the North Pacific (8), Tropical Pacific (26), and North Atlantic (27).”

“Predicted movements of skipjack during El Niño events show strong eastward directed displacement in the equatorial region, in good agreement with observations from catch and tagging data (Lehodey et al., 1997), and westward movement on either side of this equatorial band.”

“, 2007) and predatory fish (Lehodey et al., 1997).”

“Skipjack tuna in the western Pacific migrate zonally as the warm pool expands and contracts, and optimal feeding grounds shift in response to ENSO (Lehodey et al. 1997).”

“A next version will incorporate a structure to allow movement coefficients to vary over time according to season or an environmental correlate to accounting for the large-scale ENSO-related movement of tunas that have been demonstrated (Lehodey et al., 1997).”

“…breeding sites for both amphibians and birds have been ascribed to climatic warming, as have earlier egg-laying dates for birds and £owering time of plants (Beebee 1995; Crick et al. 1997; Forchhammer et al. 1998; McCleery & Perrins 1998; Crick & Sparks 1999; Post et al. 2001; Both & Visser 2001).”

“Biotic and abiotic environmental variables affect tuna distribution and abundance (Lehodey et al., 1997, Ravier and Fromentin, 2004 and Sund et al., 1981).”

“This hypothesis is in agreement with some pop-up tag records (Lutcavage et al., 1999) and several past works, which have mentioned the occurrence of other hypothetical spawning areas, such as the Ibero-Moroccan bay and the Bay of Biscay (e.g. Buen (de), 1927; 1935; Mather et al., 1995).”

“Skipjack are known to respond strongly to climate fluctuations, by expanding their range further toward the Eastern Pacific during El Ninodriven warming events (32).”

“For instance, the El Niño Southern Oscillation (ENSO), known to change drastically the oceanic conditions of the tropical Pacific Ocean, strongly affects migration, abundance and catches of tuna (Lehodey et al. 1997; Lehodey 2001; Senina et al. 2008).”

“Longline fisheries are large-scale mobile fisheries the distribution and effort of which are influenced by environmental factors and especially largescale climatic processes (Tuck et al. 2003, Lehodey et al. 1997, 2006).”

“And, the Indonesian seas are the sites of important fi sheries, such as off the Halmahera coast (western Pacifi c warm pool region; Lehodey et al., 1997) and in the upwelling region in the eastern tropical Indian Ocean along the southern coasts of Java and Sumatra.”

“However, this potently large population of PTH cannot be so widespread in the central and western Pacific Ocean.”

“Tuna distribution and abundance are sensitive to variability of environments and associate strongly with the high density of forage (e.g., Sund et al., 1981; Lehodey et al., 1997).”

“Other South American and Pacific Rim countries experience El Niño impacts on fishing (see, e.g., Lehodey et al., 1997), and other sectors in Chile, Colombia, Ecuador and Peru are also directly impacted by climate variability.”

“For several of the smaller Pacific island countries and territories (PICTs), fish is their most important renewable resource, with tuna stocks a particularly valuable asset (Bell et al. 2009).”

“…and Busalacchi, 1998; Vialard and Delecluse, 1998a; Vialard et al., 2002; Durand et al., 2002], (3) its connection with biogeochemical processes and the carbon cycle [Stoens et al., 1999; Inoue et al., 1996; Loukos et al., 2000], and (4) its relationship with tuna fisheries [Lehodey et al., 1997].”

“Use of oceanographic data allows the model to reflect the impact of ocean temperature, currents and primary production anomalies associated with El Niño or La Niña events, which results in changes of population abundance and distribution -from juveniles to adults (see Lehodey et al., 1997).”

“For example, the abundance fluctuations, distributions and migrations of tropical tuna species (e.g., skipjack, yellowfin, bigeye, albacore) have been shown to be sensitive to environmental variability (Lehodey et al., 1997).”

“purse seine fisheries in the western Pacific has demonstrated that one of the most successful fishing grounds is located in the vicinity of a convergence zone between the warm (>28-29°C) low-salinity water of the warmpool and the cold saline water of equatorial upwelling in the central Pacific ( Lehodey et al., 1997 ).”

“…of a broad array of fishery resources (Wooster and Fluharty 1985; Caviedes and Fik 1992; Agüero and Gonzalez 1996; Bakun 1996; MacCall 1996; Lehodey et al. 1997; Lluch-Cota, Hernández, and Lluch-Cota 1997; Hollowed, Hare, and Wooster 2001;Yañez et al. 2001; Pontecorvo 2001; Lehodey, Chai,…”

“To examine the possible importance of temperature effects, many have examined the distribution patterns of organisms for clues (see references in Kennedy 1990; Ware 1995; Lehody et al. 1997; Peterson & Estes 2001).”

“longitudinal location of fishing vessels (L) and standardized CPUE (Lehodey et al. 1997):”

“For example, the distribution of skipjack tuna in the western Pacific Ocean is linked to large, zonal displacements of the equatorial warm pool (e.g., Lehodey et al. 1997).”

“The vertical and horizontal distributions of pelagic species are commonly believed to be influenced by temporal and spatial trends in environmental conditions (Sharp 1978; Lehodey et al. 1997), which has led to a substantial amount of research on the habitat preferences and physiological limitations of these species (…”

“Furthermore, ENSO episodes result in broad-scale movements of apex predators in the Pacific Ocean, following transient foraging grounds (Lehodey et al. 1997, Worm et al. 2005), and declines in seabird (Hays 1986, Schreiber & Schreiber 1989) and pinniped (Trillmich & Limberger 1985) populations in…”

“Skipjack tuna are known to be strongly affected by macro-marine conditions, e.g., El Niño and La Niña (Lehodey et al., 1997; Lehodey et al., 2013; Loukos et al., 2003); however, the same changes as in other fish species were not reported for skipjack tuna.”

“This constitutes another source of modulation, which may in turn be affected by the climate through changes in catchability and fishermen’s behavior (4).”

“irregular foraging grounds in the EP, which cause broad-scale movements of apex predators in the Pacific Ocean in response to patchy prey distribution (Lehodey et al. 1997), and declines in seabird (Schreiber and Schreiber 1989; Hays 1986) and pinniped (Trillmich and Limberger 1985) populations.”

“Yet there are indications that oceanic top predators such as tuna and billfish can react sensitively to changes in climate and may redistribute quickly following El Nin˜o perturbations (for example, Sund et al. 1981; Lehodey et al. 1997 ).”

“Given that spatial distributions of many pelagic marine fishes are closely linked to dynamic oceanic features (Lehodey et al. 1997), it is not clear whether an effective spatial closure can be implemented.”

“…Walker 1923, 1924; Shukla and Paolino 1983; Swetnam and Betancourt 1990; Nicholls 1993; Aidiku and Stone 1995; Stone et al. 1996; Eltahir 1996; Lehodey et al. 1997; Ward 1998; Chiew et al. 1998; Maelzer et al. 1999; Power et al. 1999; Linthicum et al. 1999; Pascual et al. 2000; Chu and He…”

“Our study framework is motivated by the following considerations: (1) ocean Chlorophyll (Chl) represents a measure of biomass at the lowest levels of the ocean food chain, and at least at lower frequencies is shown to affect top predators such as fish [ Lehodey et al., 1997; Chavez et al., 2003], (2) surface Chl is an…”

“In the western Pacific, the highest abundance of skipjack tuna is strongly related to the movement of specific SST isotherm (29 C), which seems to be a reasonable proxy for front and convergence zones [Lehodey et al., 1997].”

“…due to heavy fishing and redistribution or declines in abundance due to large-scale interannual and longer-term oceanographic fluctuations (e.g. Lehodey et al. 1997, Karl et al. 2001, Polovina 2005) could reduce skipjack abundance within the foraging range of seabirds, especially during the…”

“PICTs also have to cope with the effects of the El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation on the benefits they receive from the abundant skipjack tuna—the prime fishing areas for this species change by up to 3,000–4,000 km depending on the prevailing ENSO conditions (Lehodey et al. 1997; Leho…”

“The concentration of chlorophyll-a is a measure of biomass at the lowest levels of the ocean food chain, which has been shown to affect top-level predators such as fish (Lehodey et al., 1997).”

“During El Nin˜ o events, the cold tongue (and the associated zone of high skipjack abundance) retreats eastward—by as much as 4000 km depending on the intensity of the event [ 20 ].”

“This results in a distribution of effort encompassing more or less the fleet search area and attenuates interannual variations linked e.g., to El Nin ˜ o events, which are known to significantly impact the fishery ( Lehodey et al., 1997 ).”

“change in skipjack average abundance occurs a few months following an ENSO phase, and in subsequent years for adult albacore) (Lehodey et al., 1997; Lehodey, 2004; ISC, 2010).”

“However, the complex relationships among tuna and oceanographic variation remains poorly understood (Harrison & Seki 1987, Lehodey et al. 1997, Lu et al. 2001).”

“Given the substantial amount of published literature on impacts of regime shifts on fish productivity [33,62–66], it seems intuitive that accounting for ecosystem regime shifts and states in harvest control rules should improve the ability to optimize the balance between yield and conservation [67,68].”

“S2; Martin et al., 2005).”

“…(March 1997) so nekton and nekton (Yarnamoto & Nishizame 1986, that the present results might not have been signifi- Power 1996, Kimura et al. 1997, Lehodey et al. 1997). cantly influenced by the climatic change that oc- Our measurements of the depth of the photic layer curred. illustrates this…”

“For example, distribution of the Skipjack Tuna Katsuwonus pelamis increased with the expansion of the ENSO warm pool, and the Skipjack Tuna fishing grounds extended to 6,000 km along the equator (Lehodey et al. 1997); furthermore, distribution areas of the Peruvian Anchovy Engraulis ringens extended to southern Peru,…”

“There is good evidence that ENSO events have an impact on the recruitment of tuna, their distribution, composition, and species abundances [Lehodey et al., 1997; Lumban-Gaol et al., 2002; White et al., 2004].”

“…gravity centres of fishing effort, which described the characteristics of the north–south migration of chub mackerel, were calculated following Lehodey et al. (1997): Gi ¼ P ðLi EiÞP Ei ; (8) where Li is the latitude of the midpoint of the ith 0.17 × 0.17° cell and Ei is the total fishing…”

“tribution of skipjack tuna may vary with the El Niño-Southern Oscillation (ENSO), with an eastwards shift in core distribution to the central Pacific Ocean (CPO) under El Niño conditions (Lehodey et al., 1997).”