HUMAN VISITATION AND THE FREQUENCY AND POTENTIAL EFFECTS OF COLLECTING ON ROCKY INTERTIDAL POPULATIONS IN SOUTHERN CALIFORNIA MARINE RESERVES

Humans intensely use southern California rocky shores for recreational activities such as fishing, exploration, wallung, enjoyment of the out-of-doors, and educational field trips. People also collect intertidal organisms for consumption, fish bait, home aquariums, and other purposes. In Orange County, visitors concentrate their activities on a few rocky headlands and reefs. Many of these shores have been designated as California Marine Life Refuges (CMLRs) or State Ecological Reserves (SERs), where the removal of most intertidal organisms, except for scientific purposes, has been unlawful for 30 years. In a yearlong study of eight Orange County shores, unlawful collecting of organisms was often observed. In addition, lifeguards have frequently observed unlawful collecting on these and other shores. The CMLR or SER designation &d not deter collecting. Mussels, trochd snails, limpets, urchins, and octopuses were the most commonly collected organisms, primarily for food or fish bait. Several of the gastropod species targeted by human collectors had low population densities and population structures dominated by smaller and less fecund individuals, characteristics that often occur in populations exploited by humans. Most collected invertebrates were broadcast spawners that require high densities of fertile individuals to optimize reproduction. The cascading effects of collecting on community structure and the reproductive success of exploited populations are unknown. Except for state park rangers at one site, no state enforcement personnel were seen during 768 hours of low-tide observations throughout the year. Without effective enforcement, adequate signage, and educational programs to increase public awareness, CMLRs and SERs are not protecting rocky intertidal populations on heavily visited southern California shores. Improved management practices are needed if CMLRs and SERs are to protect rocky intertidal populations and to serve as benchmark sites where changes in populations due to regional climatic events or chronic human disturbances can be measured and evaluated in the absence of exploitation.

[1]  D. Schiel,et al.  Effects of trampling on a rocky intertidal algal assemblage in southern New Zealand , 1999 .

[2]  P. Brown,et al.  Effects of trampling by humans on animals inhabiting coralline algal turf in the rocky intertidal , 1999 .

[3]  J. Estes,et al.  HUMAN INFLUENCES ON TROPHIC CASCADES ALONG ROCKY SHORES , 1998 .

[4]  O. A. Pombo,et al.  Effect of Exploitation on the Limpet Lottia gigantea: A Field Study in Baja California (Mexico) and California (U.S.A.) , 1996 .

[5]  M. Tegner,et al.  Near extinction of an exploited marine invertebrate. , 1996, Trends in ecology & evolution.

[6]  L. Addessi.  Human Disturbance and Long-Term Changes on a Rocky Intertidal Community , 1994 .

[7]  D. Brosnan,et al.  Effects of human trampling on marine rocky shore communities , 1994 .

[8]  G. Quinn,et al.  Correlations between human collecting and intertidal mollusc populations on rocky shores , 1993 .

[9]  S. Distefano,et al.  Biological Consequences of Topography on Wave-swept Rocky Shores: I. Enhancement of External Fertilization. , 1992, The Biological bulletin.

[10]  M. Keough,et al.  Effects of trampling on plant and animal populations on rocky shores , 1991 .

[11]  A. Underwood,et al.  Humans as predators on rocky reefs in new south wales australia , 1991 .

[12]  L. Durán,et al.  Variation and persistence of the middle rocky intertidal community of central Chile, with and without human harvesting , 1989 .

[13]  A. Dye.  Rocky shore surveillance on the Transkei coast, southern Africa: temporal and spatial variability in the balanoid zone at Dwesa , 1988 .

[14]  C. Catterall,et al.  The potential impact of human gathering on shellfish populations, with reference to some NE Australian intertidal flats , 1987 .

[15]  J. Castilla,et al.  The effect of human exclusion on the population structure of key-hole limpets Fissurella crassa and F. Limbata on the coast of central Chile , 1986 .

[16]  P. Hockey,et al.  Man as an Intertidal Predator in Transkei: Disturbance, Community Convergence and Management of a Natural Food Resource , 1986 .

[17]  J. Castilla,et al.  Human exclusion from the rocky intertidal zone of central Chile: the effects on Concholepas concholepas (Gastropoda) , 1985 .

[18]  P. Hockey,et al.  Exploitation and Conservation of Brown Mussel Stocks by Coastal People of Transkei , 1985, Environmental Conservation.

[19]  K. Beauchamp,et al.  A quantitative assessment of human trampling effects on a rocky intertidal community , 1982 .

[20]  G. T. Boalch,et al.  A Resurvey of Colman's Intertidal Traverses at Wembury, South Devon , 1974, Journal of the Marine Biological Association of the United Kingdom.

[21]  S. Murray.  Effectiveness of Marine Life Refuges on Southern California Shores , 1998 .

[22]  S. Wells.  Giant clams : status, trade and mariculture, and the role of CITES in management , 1997 .

[23]  T. Agardy.  Marine protected areas and ocean conservation , 1997 .

[24]  C. Griffiths,et al.  THE EXPLOITATION OF COASTAL INVERTEBRATES AND SEAWEEDS IN SOUTH AFRICA: HISTORICAL TRENDS, ECOLOGICAL IMPACTS AND IMPLICATIONS FOR MANAGEMENT , 1997 .

[25]  Paul C. Ticco.  The use of marine protected areas to preserve and Enhance marine biological diversity: A case study approach , 1995 .

[26]  S. Gubbay.  Marine protected areas — past, present and future , 1995 .

[27]  B. Causey.  Enforcement in marine protected areas , 1995 .

[28]  L. Newton,et al.  The effects of shell collecting on the abundance of gastropods on Tanzanian shores , 1993 .

[29]  M. Littler,et al.  Southern California rocky intertidal ecosystems , 1991 .

[30]  S. Ortega.  THE EFFECT OF HUMAN PREDATION ON THE SIZE DISTRIBUTION OF SIPHONARIA-GIGAS (MOLLUSCA, PULMONATA) ON THE PACIFIC COAST OF COSTA-RICA , 1987 .

[31]  C. Moreno,et al.  Man as a predator in the intertidal zone of southern Chile , 1984 .

[32]  J. Devinny,et al.  Alternation of Southern California rocky shore ecosystems by public recreational use. , 1983 .

[33]  A. Mclachlan,et al.  GROWTH AND PRODUCTION IN EXPLOITED AND UNEXPLOITED POPULATIONS OF A ROCKY SHORE GASTROPOD, TURBO-SARMATICUS , 1981 .

[34]  R. Thom,et al.  A Resurvey of E. Yale Dawson's 42 Intertidal Algal Transects on the Southern California Mainland after 15 Years , 1978 .

[35]  G. M. Branch,et al.  Notes on the Ecology of Patella Concolor and Cellana Capensis, and the Effects of Human Consumption on Limpet Populations , 1975 .

[36]  T. B. Widdowson.  Changes in the Intertidal Algal Flora of the Los Angeles Area Since the Survey by E. Yale Dawson in 1956-1959 , 1971 .