Composite Training Unit Exercises and Joint Task ... - Govsupport.us

COMPTUEX/JTFEX EA/OEA Final Chapter 3along the west coast of North America. South of Point Conception, adjacent to the Southern CaliforniaBight, the California Current breaks away from the coast and flows offshore along the continental edgeuntil it swings back toward the mainland south of San Diego. In the Southern California Bight, the usualsurface flow, called the California Countercurrent, moves north along the coast resulting in acounterclockwise gyre that mixes offshore and nearshore surface waters (CDFG, 2001).The California Current is a dynamic system with considerable variation over time. Relatively short-term,dramatic events like El Niño (warmer water) and La Niña (cooler water) cause significant temperaturechanges, variation in productivity, and occurrences of organisms beyond their usual ranges. Long-termtemperature regimes, periods of slightly warmer or cooler conditions that persist for decades, can affectreproduction and recruitment of marine species like sardines and rockfish for several generations andresult in substantial changes in abundance over time (CDFG, 2001).The offshore ecosystem is home to Coastal Pelagic Species (CPS) (sardines, anchovy, mackerel, andsquid); highly migratory species (tuna, bill fishes, and pelagic sharks); ground fish species (shelf andslope rockfish, flat fish, sable fish, and Pacific whiting); marine mammals (such as whales and porpoises);and pelagic seabirds (including albatross and shearwaters) (CDFG, 2001).The pelagic zone, relating to open water, is the largest habitat in the study area with 40 percent of the fishspecies inhabiting this area. This zone is subdivided into three distinct regions: epipelagic (up to 50 mdeep), mesopelagic (50 to 500 m deep), and bathypelagic regions (greater than 500 m deep) (Cross andAllen, 1993). The epipelagic region is inhabited by small, planktivorous schooling fish (e.g., northernanchovy), predatory schooling fishes (e.g., Pacific mackerel), and large solitary predators (e.g., blueshark). Abundance of all epipelagic species changes seasonally with fishes moving offshore to spawn.The northern anchovy is the most abundant epipelagic species in the study area. The mesopelagic regionis characterized by steep environmental gradients and fishes that are small, slow-growing, long-lived, andreproduce early and repeatedly (e.g., bigeye lightfish). The bathypelagic zone is a rather uniform systemcontaining large, sluggish, fast growing, short-lived fishes, that reproduce late and typically only once(e.g., bigscale and hatchetfish ) (Cross and Allen, 1993).Typical fishes utilizing soft substrates (sand, silt, and mud) include sharks, skates, rays, smelts, flatfish(flounders), gobies, and northern anchovies (Allen et al., 1992; Pondella and Allen, 2000; U.S. Navy,2002a). Regions with hard substrates and kelp beds (Macrocystis) are not as abundant as other benthichabitats in the Southern California Bight, but they nevertheless provide important habitats for manyspecies. Shallow reefs (i.e.,