FAO Fisheries Circular No. 920 FIRM/C920
REVIEW OF THE STATE OF WORLD FISHERY RESOURCES: MARINE FISHERIES
Marine Resources Service,
Fishery Resources Division,
FAO, Rome, Italy
13. EASTERN CENTRAL PACIFIC
FAO Statistical Area 77
This Statistical Area covers fishery resources and fisheries off the western coastline of the Americas from northern California, USA, to southern Panama (Figure B13.1). It has a total extension of 48.90 million km2 and a total shelf surface of 0.81 million km2. Most of the continental shelf is narrow, and hardly extends more than 20 km from the coastline, except for some areas off San Francisco Bay, El Salvador, Nicaragua and the Gulf of Panama, where it widens to as much as 60 km. The bottom tends to be heterogeneous, with several areas suitable for trawling, although there is not much trawl fishing except for shrimps. Trawling for coastal demersals is very limited, and deep-water trawling is almost non existent. There are a few small coastal islands off southern California and Panama, and other island groups in oceanic waters. These island chains, of which the largest one is Hawaii, also have very narrow continental shelves.
The area is under the influence of two major surface current systems, the California Current in the north and the Equatorial Current in the south. The interaction between current systems, the topography and the differences in wind stress generate major upwellings along the coast of California, Baja California, the Gulf of Panama, and some smaller upwellings along the Central American coast and offshore in the Costa Rica dome. While coastal upwelling tends to be particularly important in the northern, more temperate part of the area, coastal runoff tends to be another major source of coastal water enrichment along the more tropical areas off Central America. These characteristics strongly influence the abundance and distribution of fishery resources and fishing activities. Fishing for small and large pelagics is particularly important at or around the major upwelling areas, and fishing for shrimps and, to a lesser extent, for coastal demersals sustain major local fisheries in the more tropical areas off Mexico, Central America and Panama.
PROFILE OF CATCHES
In 1994 the total production per shelf area was 1.67 t/km2. This rather high value is mostly due to the production of small and large pelagics, some of which don't have their life histories restricted to the neritic shelf area. When only shelf-dependent species are considered, the total production per shelf area drops to 0.74 t/km2, which is still amongst the highest overall value for a tropical and sub-tropical shelf area. As with the total catches, historic and current production per shelf area come mostly from pelagics, followed by much lower volumes of squids, shrimps and coastal demersals. Pelagic fisheries are particularly important off southern California, Baja California, the Costa Rica dome and the Gulf of Panama. Although shrimp catches are limited, their high unit value makes shrimp fishing the other major commercial fishery in the area and the main one in most of the coastal countries in the area.
Some pelagic fisheries were already quite developed in this area during the first half of this century, particularly off California. Total catches of tunas were in the order of 150 000 t per year prior to the 1950s, and catches of California pilchard (or sardine) (Sardinops sagax caeruleus) reached peaks well over 700 000 t in the 1930s and early 1940s. In those years the total accumulated production from this area rose to peaks around 900 000 t but, after some very good years, total catches dropped sharply to a record low of 320 000 t in 1953. Most of this was caused by the bloom and collapse of the California sardine fisheries off the USA.
Since 1953 total catches for the whole area had a sustained rate of increase, peaking at 1.9 million t in 1981. Since then total catches and catches by major species groups have been very variable and with a general decreasing trend, although from 1993 to 1994 the total production increased slightly from 1.27 to 1.33 million t (Fig. B13.2, Table XIII). While most of the recent year-to-year variability and decreasing trend in total production has been due to the changes in the abundance and overall production of small pelagics, it is noteworthy that the strong 1983-84 "El Niño" caused a severe drop in total catches of almost all species groups.
From the total resource base point of view, the collapse of the California pilchard (sardine) fishery off California in the late 1940s was compensated by an increase in the abundance of California anchovy (Engraulis mordax) in the same general location, although no substantial fishery for this species developed until much later. It was only by the 1970s that Mexico developed a major industrial fishery for California sardine and California anchovy, which contributed to increase the total production of small pelagics in Group 35 from the record low of 36 000 t in 1952, to a peak of almost 900 000 t in 1980 (Fig. B13.3). Total catch of small pelagics in this ISSCAAP Group then declined with some year-to-year variability to only 323 000 t and 387 000 t respectively in 1993 and 1994. Most of this recent decline is due to the reduced abundance and lower catches of California sardine, and particularly of California anchovy. Catches of California sardine dropped from 509 000 t in 1989 to 194 000 t in 1993, to increase slightly to 266 000 t in 1994. However, in recent years the most dramatic change in overall abundance and production has been that shown by the California anchovy. Catches of this species dropped from a peak of 424 000 t in 1981 to the record low of 3 900 t in 1994.
Other important small pelagics of ISSCAAP Group 35 in this area are the Pacific anchoveta (Cetengraulis mysticetus) and the Pacific thread herring (Opisthonema libertate), caught mostly off Panama. Catches of these two species are highly variable. The maximum recorded catch of Pacific anchoveta was 241 000 t in 1985, followed by low values of the order of 39 000 and 62 000 t in 1988 and 1990, and 72 000 t in 1994. The maximum recorded catch of Pacific thread herring was 40 000 t in 1988, followed by 18 000 t in 1989 and a new high of 41 000 t in 1994 (Figure B13.3).
The other main small pelagic species in this area are the Pacific jack mackerel (Trachurus symmetricus) in ISSCAAP Group 34, and the chub mackerel (Scomber japonicus) in ISSCAAP Group 37. These two resources have sustained important fisheries off the USA since the beginning of the century. In the available statistics (Fig. B13.4) catches of Pacific jack mackerel peaked at 66 000 t in 1952 but have been highly variable, with a clear decreasing trend in recent years. Very low catches of 1 200 to 2 700 t have been reported between 1992 and 1994. Catches of chub mackerel have also been very variable, with more prolonged periods of high and low catches. Observed high catches peaked at 67 000 t in 1935, 34 000 t in 1956 and, more recently, at 78 000 t in 1990, following a period of almost negligible catches in the early 1970s.
Tunas and other large pelagics are an important group with an extended distribution in the area. Their total production had a sustained and fast rate of increase until the 1970s, and has been increasing slightly with some fluctuation in the range of 283 000 t to 516 000 t per year over the past two decades (Figure B13.5). In 1994 the total catch of this species group was 413 000 t. In the region, the main fishing countries are Mexico and USA. Other principal countries fishing here are Venezuela, Japan, Rep. of Korea and other Asian countries. The main species are the yellowfin tuna (Thunnus albacares), which over the past few years has been yielding relatively stable catches of the order of 210 000 t to 280 000 t per year, with 234 000 t in 1994, and the bigeye tuna (Thunnus obesus), that has been yielding total catches of 70 000 t to 100 000 t per year, with 77 000 t in 1994. Catches of skipjack tuna (Katsuwonus pelamis) and albacore (Thunnus alalunga) are also important and have been relatively stable, with total reported catches of 52 000 t and 12 000 t respectively in 1994.
Shrimps and prawns sustain particularly valuable and important fisheries throughout the area. Total production of this species group has been increasing almost steadily to a maximum of 100 000 t in 1994, but most of the recent increase is due to the expansion of aquaculture production. Total shrimp catches have been more or less stable, ranging in recent years between 50 000 t (in 1990) and 80 000 t (in 1985) per year (Fig. B13.6). It is noteworthy, however, that these represent the accumulated catches of a large number of stocks and 7 to 10 species (mostly Penaeus spp) that individually tend to be more variable but are not properly identified in most of the available landing statistics. Catches of squids have also been variable. After a rapid increase to a peak at 75 000 t in 1988, total catches of squids decreased to 30 000 t in 1992 to increase to 56 000 t in 1994 (Fig. B13.6). Although not specifically identified in the landing statistics, a good share of what is reported as squids nei for this area is currently the jumbo flying squid (Dosidicus gigas).
There is no ongoing directed fishery for deep-water demersals in the area, and most of the reported catches of other more coastal demersals (mostly in ISSCAAP Group 33) are taken by small local fleets. Nevertheless, the effective fishing effort actually directed on to these stock is very limited, and the reported catches are frequently of by-catches from the shrimp fisheries.
RESOURCES STATUS AND MANAGEMENT
Tunas and squids in this area are exploited both by local fleets and by long-range fleets from different nations, while most other fisheries are exploited by local fleets from nations bordering the area. Except for tunas, which are assessed and managed through multinational efforts, and some bilateral or regional research activities on other species groups, so far of limited duration and scope, most fisheries in the area are assessed and managed through national initiatives.
The Inter-American Tropical Tuna Commission (IATTC) based in La Jolla, California, has a long lasting tradition and experience in assessing and managing the main tuna stocks, and while not all countries in the area are members, it is still the main regional organization devoted to fisheries research, assessment and management of tunas in the Eastern Central Pacific. Several bilateral programmes addressing fisheries assessment and management issues have been executed in the past, and some are still ongoing between the USA and Mexico, particularly with respect to small and large pelagics in the California and Baja California area.
There have also been a series of regional research activities covering fish stocks and fisheries further south, off Central America and Panama. Several of these activities have been conducted or are still going on under regional cooperation programmes with the technical and/or financial assistance of one or more international, regional or sub-regional organizations, such as EC, FAO, NORAD, OLDEPESCA, PRADEPESCA and UNDP. While in some cases scientific progress has been achieved through these fisheries research and assessment programmes, less has been accomplished in terms of fisheries management. In this respect, it is worth noticing that, as of 18 December 1995, all the Central American countries created a new regional fisheries organization, the "Organización del Sector Pesquero y Acuícola del Itsmo Centroamericano" (OSPESCA) that has the development and management of fisheries in the area as one of its main objectives.
As far as more specific assessments and management-related information is concerned, it is noted that very few research efforts have been devoted to studying the deep-water demersals of ISSCAAP Groups 32 and 33, which, besides being poorly studied, are also almost unexploited in this area. There are, however, no indications that particularly abundant stocks of these species groups might exist in the area. Coastal demersals, mostly in ISSCAAP Group 33, are in most cases moderately exploited if one considers their directed fisheries, but tend to be heavily to over-exploited by the shrimp fisheries, where demersal fish frequently represent a large proportion of the by-catch, especially as juveniles.
It has been already reported that, within ISSCAAP Group 35, the total catches and overall abundance of California sardine and California anchovy have been very variable and are currently down to fairly low levels. The California sardine seems to be well below its maximum historical abundance levels, and while off Mexico is probably fully exploited, it is currently underexploited off the USA. The California anchovy is seriously depleted, after being fished heavily for several years off Mexico, and very lightly exploited or under-exploited off the USA. Although these two species have been subject to heavy exploitation rates in same parts of their distribution range, the recent declines in overall abundance and total production seem to be related to a large extent to natural "regime" changes also reported for similar species elsewhere (see later special topic on "Global synchrony in fish population variations").
The Pacific anchoveta stock has also been very variable, as reflected by the annual catches by Panama, where it sustains a major industrial fishery. This stock is probably moderately to fully exploited. Pacific thread herring is only reported in substantial quantities by Panama, where there is a directed fishery for this species. In the past, a small fleet from Costa Rica used to also target on Pacific thread herring, but this species now mostly shows up in incidental catches throughout the area. This stock is probably moderately exploited off Panama and under-exploited elsewhere in its distribution range.
Other small pelagics in ISSCAAP Groups 34 and 37 are only moderately exploited, while most tunas within ISSCAAP Group 36 are considered to be fully exploited.
Amongst the invertebrates, there are some deep water shrimps (mostly Galatheidae) within ISSCAAP Group 44 which are virtually unexploited, while most, if not all, the main wild stocks of shrimps and prawns in ISSCAAP Group 45 are either fully or over-exploited, with several giving clear signs of stock depletion. Still within the invertebrates, squids (ISSCAAP Group 57) seem to also be relatively abundant in the area but are virtually unexploited, or underexploited in some areas.