UC San Diego IMR Reference Title Fish life in the kelp beds and the effects of kelp harvesting Permalink https://escholarship.org/uc/item/4w36x6mb Author Limbaugh, Conrad Publication Date 1955-09-09 eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA INSTITm OF MINE FiESOURCES La Jolla, California FISH LIFE IN THE KEIS BEDS AND THE EFFECTS OF KELP HARVESTING Conrad Limbaugh Final r&-' of results of investigations conducted from 1948 to 1954 under Fellowship Grant from Kelco Company IMR Reference 55-9 9 September 1955 ) Supervisor of Research . Charles D. Wheelock Director L imbaugh IMR Bef . 55-9 TABU OF CONTENTS Page Introduction ...................... 1 The Kelp Plant and the Kelp Beds ............ 3 The Kelp &%bita.tas an Envj-ronment for Fishes ..... 6 The Life Histo~yof ........ 12 me Possible Origir, & Macrocystis pyrifers on the California Coast ................. Kelp as a Factor in Submarine Erosion ......... The Kelp-Bed Biotopes ................. The canopy biotope ................ The kelp-bed bottm biotopes ........... The kelp -bed sand-bott om b iotope ....... The kelp-bed rock-bottom biotope ....... Organisms of the mid -kelp blot ope ......... The Effects of Harvesting on Kelp Beds ......... Effects of Kelp Harvesting on Fish Life ........ Fish Tra~pingand Tagging ............... Summary and Conclusions ................ Suggestions for Future Studies ............. Appendix Sabits of the fishes found in the kelp beds of Southern California ............- Invertebrates of the kelp-bed canopy biotope ... Invertebrates of the kelp-bed sand-bottom b i0tOpe . Common ma^. i9e plants of the kel?-bed rock-bottom biotope ................... Inver%ebrat,ss of t.? it? ke'i.p-'r,ed r ock.bo%t. om biotge . iii . n\lR Ref. 55-9 INTRODUCTION This final report is the result of research during the five and one- half year period frm Se~tember1948 to Masch 1954. Modern techniques and equipment were utilized. and were in part d.evdoped especially for this problem. Throughout the investigation the apparent decline of sport fish was causing sport fishermen peat concern. Among other factors, kelp harvesting was blamed for the poor catch of the sportsman. Early methods of investigation were primitive. With limited financial support and insufficient eqtiipment , the investigation proceeded at a slow rate and many of the problems encountered seemed insurmountable. More than a year after the beginning of this investigation, the Kelco Company approached the Scripps Institution of Oceanography of the University of Califarnia, with the request that the problems of kelp cutting in relation to the fish supply be attacked by the University under a fellowship grant, by unprejudiced research. The Company wanted to determine whether the kelp operations were adversely affect- ing fishing, and if so, how harvesting methods might be altered to prevent this. The grant of' money given the University provided my salary and funds to purchase research supplies, equipment, ar-d services. With this aid, along with the laboratory and ship facilities at Scripps Insti- tution of Oceanography, I was able to carry out a much mare extensive research program. The investigation was carried out with the coop- eration of the California Department of Fish and Game. The first phase of the program was concerned with observation and identification. Thousands of hours were spent above and below the surface observing the organism in their own environment. Extensive use was made of self-contained diving equipment for observations, collect ion, and placing of equipment. Underwater photography was developed to a point where many observations could be recorded. The second phase of the program was to appraise the effects of kelp harvesting on fish life. All materials ox ideas furnished by sports- men were given consideration. Because of the lack of pertinent published data on the ecology of the inshore waters, it was necessary to investigate not only the beds of the main commercial kelp (~acroc~stisp~rifera) , but also many other regions, in order to obtain comparatzve data. Such areas included bays, rocky areas below the levels where kelp grows, rocky areas with no kelp, the surf zones, sandy areas, and regions outside the West Ccast range of Macrocyst is . L imbaugh -2- IMR Ref. 55-9 Kelp beds were studied as far north as Monterey and as far south as the San Benito Islands, Ba33 California. Diving observations in the kelp were made at Iulonterey, Morro Bay, Goleta, Santa Barbara, Point Dume, Palos Verdcs, Newpart, Laguncl, Dana Point, San Clemente, Del Mar, Solana Beach, La Jolla, Point Lorna, Ensenada, Punta San Carlos, Punta Blanca, Punta Santa Rosalia, and numerous other points along the mainland; also at San Miguel, Santa Rosa, Santa Cruz, Anacapa, Santa Catalina, Coronado, San Martin, and San Eenito Islands. Intensive studies of the problem were carried out in Orange a?d San Diego Counties, with special concentra- tion on the nearby La Jolla kelp beds (~ig.1) . One portion of the La Jolla kelp beds was left uncut as a control. Little difference has been noted in the fish life within the bed as contrasted with harvested beds. The kelp itself became more sparse, probably because of reduced light penetration through the heavy canopy that developed tem- porarily. In the 1952-53 winter season (~ig.2) much of the kelp was de- stroyed by storms. These studies yielded a vast amount of information bearing not only on the kelp problem but also on the life ways of the fishes. Such information is a material contribution to science and will aid in fish management in the future--for the -benefit of fishing in general. ' --As a result --of these long -and thorough studies, --it is concluded --that kelp harvesting, as currently practiced, --has no seriously ---.-detrimental effects -on fishing. The various claims as to the ways in which kelp harvesting was supposed to destroy fish life and to decrease the fish catch were completely investi- gated and found to be in error. Spawning and nursery grounds of fish are not being destroyed. Sufficient cover and food are always available during and after harvesting. The kelp beds are not destroyed by harvesting methods. Harvesters do not frighten sportfish from an area. For several decades California has experienced a tremendous increase in population. Cities have grm where deserts and foothills were the homes of deer, rabbits, ground squirrels, ground owls, doves, and quail. In most places these animals have largely disappeared, and with them the intertidal mollusks--Pismo clams, butter clams, abalone, and many other species. The shore fishes such as corbina and spotfin croaker are less common in the individual fisherman's catch. Over kelp beds where a man might have fished alone a decade or two ago, we may see 50 sport boats with a total of 1000 anglers. Thus, even though the annual catch may be the same as or higher than 10 or 20 years ago, the catch per fisherman is much lower. The kelp industries have arisen indirectly from our social-economic needs for new raw materials to fill new markets. They have become established in our economy and are essential for the production of certain new products. FIGURE 1. Aerial photograph of the La Jolla kelp beds. The lines running through the beds are the paths of a kelp harvester. The plants are anchored on a rocky bottom from a depth of 45 feet on the inner edge of the beds to a depth of 90 feet on the outer edges of the beds. The photographs were made with infra- red film which pictures only the surface kelp. FIGURE 2. Kelp torn loose from an uncut La Jolla kelp bed and deposited on the beach during the 1952-53 winter season. Limbaugh -3- IMR Ref. 55-9 As is typical of modern, young industries, they have conducted research to determine the maximum sustained yield. The industry naturally has no desire to destroy kelp. The sportfishing Industry is Mge and provides recreation, necessary for our nation's health, to thousands of' persons. With the addition of thou- sands of newcomers to sportfishing and the reduction of catch per unit of effort, it is not difficult to understand the fishermen's concern over factars supposedly destroying their sport. It is necessary, hawever, to determine the real reason for the apparent decline of fish before any constructive action can be taken. It may be a problem of overfishing or of natural pupulation fluctuations, but the blame cannot be laid to the kelp harvesting. THE I(Ef9 PLANT AND TBE KELP BEW Kelp beds are submarine forests of giant algae (Fig. 3). The major kelp beds of southern California are ccunposed of a single species of giant kelp, Macrocystis pyrifera. The distribution of' Macrocystis pyrifera along our coast is rather scattered. It is found fram Sitka, Alaska, south to Magdalena Bay, in southern Baa California, ~exico. In the northern portion of' its range it is restricted to small inshore beds, wually at the entrance: of bays or in the lee of islands. Large offshore beds are found only from Santa Cruz, California, south into central Baja California. In the more southern part of its range the warm summer waters may destroy the beds. Macrocystis is not found in abundance aqphere else in the northern hemi- sphere. In the southern hemisphere it exists in almost all temperate waters, especially in areas of nutrient -r ich upwelled water. Twisted columns of slender, round, stemlike stipee rise fram 20 to 100 feet or more, from a rootlike holdfast (~igs.4 and 7) to the growing terminal tip of the individual stipes (~ig.5). The ends of the etipes bend at the surface to fcmn a canopy, often 4 feet thick. Alternately attached to the thin unbranched stipes are leaflike blades, each with a round to egg-shaped supparting float (~ig.