The Case Against Lay Gill Nets

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					The Case Against
 Lay Gill Nets

  John E. Randall, Ph.D.
 Charles Birkeland, Ph.D.
  Richard L. Pyle, Ph.D.
  Randall Kosaki, Ph.D.

        July 2006
Dr. John Randall is the world’s leading authority on coral reef
fish taxonomy.
Dr. Charles Birkeland has studied coral reef ecology for more
than thirty years.
Dr. Richard Pyle has extensively explored deep coral reefs
throughout the Pacific.
Dr. Randall Kosaki, a lifelong fisherman, studies behavioral
ecology of coral reef fishes.
Lay Gill Nets Should be Banned

        The State of Hawai‘i Department of Land & Natural Resources (DLNR) is
proposing to strengthen regulations on lay gill nets as a fishing method. The proposed
rules affect gill nets that are set and often left unattended to ensnare fishes. The rules do
not affect free-floating, not weighted to the bottom, netting practices such as used by
fishermen for targeted species like ‘ōpelu (mackerel scad).

        As marine scientists, we think this is a very positive step forward in protecting
Hawaii’s dwindling nearshore resources. The total biomass of reef fishes in the Main
Hawaiian Islands is less than a quarter of what it was a century ago.1 While pollution,
development, and alien species are possibly all contributing to this loss, overfishing is the
primary factor in the precipitous decline of our nearshore fisheries. 2 When done
responsibly, there are many ways to fish sustainably, such as pole and line, handline,
throw net, and breath-hold spearing. However, our populations of fishes cannot be
sustained if large-scale, indiscriminate and damaging fishing methods, such as use of lay
gill nets, are allowed to continue.
                                                                                                                Ulua - Jacks
Overfishing Is a Chief Threat                                   500x103
        Anyone who has dived in the Northwestern                100x103

Hawaiian Islands, as three of the authors have, is               20x103

immediately struck by the abundance of the larger                15x103

fishes, especially the jacks and sharks, compared to             10x103

the Main Hawaiian Islands. Because of the distance                5x103              Figure 1
from the population center in the main islands, the                      0
                                                                              1900     1920      1940    1960      1980       2000
northwestern islands have been spared much of the
impact of overfishing. The average biomass of                   60x103

                                                                                        kumu - Whitesaddle Goatfish
important large predators, such as sharks and jacks,            50x103                  (Parupeneus porphyreus)
is 65 times as great as that in the Main Hawaiian
Islands.3                                                       40x103

         The populations of important native food               30x103

fishes in the Main Hawaiian Islands have declined               20x103

at least 75 percent over the past 100 years.4 This is
especially apparent upon review of commercial                                        Figure 2
catch data from 1901 and from 1949-2000 for                          0
                                                                             1900     1920      1940    1960      1980    2000

  Birkeland, C. and A.M. Friedlander. 2002. The Importance of Refuges for Reef Fish Replenishment in
Hawai‘i. Hawai‘i Audubon Society and Pacific Fisheries Coalition, Honolulu, Hawai‘i.
  Shomura, R.S. 1987. Hawaii’s marine fishery resources: yesterday (1900) and today (1986). Southwest
Fisheries Center Administrative Report H-87-21. 15.; Harman, R.F. and A.A. Katekaru. 1988. Hawai‘i
commercial fishing survey: summary of results. State of Hawai‘i, Department of Land and Natural
Resources, Division of Aquatic Resources Report. Honolulu, Hawai‘i. In: Birkeland, C. and A.M.
Friedlander. 2002
  Friedlander, A.M. and E.E. DeMartini. 2002. Mar. Ecol. Prog. Serv. 230, 253.
  Birkeland, C. and A.M. Friedlander. 2002.

fishes such as ulua (jacks), kūmū (goatfish), and
moi (threadfin). See, Figures 1-3.5 It’s notable that                                    Moi – Threadfin
                                                                                         (Polydactylus sexfilis)
monofilament lay gill nets were introduced in
Hawai‘i in the 1950s.

        Further, most fishes in the Main Hawaiian
Islands are now caught before they reach their full
reproductive potential. Many reef fishes here reach            Figure 3
reproductive maturity late in life, e.g., ‘u‘u
(soldierfishes or menpachi) at age 6. Also, in many
species the older fishes contribute higher numbers of bigger and better quality eggs, e.g.,
‘ōmilu (bluefin trevally) and moi. In a 1997 study, it was reported that 97 percent of
‘ōmilu caught in Hanalei Bay had not reached sexual maturity.6 ‘Ōmilu do not reproduce
until they reach 12 inches. However, if allowed to grow, a 27-inch female ‘ōmilu will
produce 84 times as many eggs as a 12-inch female.7


        Fishing in nearshore waters changed dramatically in the 1950s with the
introduction of the modern, monofilament lay gill net. Previously, traditional gill nets
were very valuable and hence carefully used. The expert net maker had to barter with
dogs, fish, and kalo for enough painstakingly scraped and shredded olonā fiber to make a
net. His wife had to twist the fiber into cordage before the net could be made. Usually,
the nets were deployed at high tide at night across shallow, sandy places in the reef where
certain kinds of fish were known to run with the changing tide. One or two men worked
the net on the seaward side, feeling when a fish was caught and removing it immediately.
With this type of fishing, only the kinds of fish desired, in the numbers needed, would be
                                          caught. The net was left in the water only as long
                                          as those fish were running.8

                                                Because modern monofilament gill nets
                                        are relatively inexpensive, costing around $100,
                                        fishermen are more willing to risk the loss of their
                                        nets. This has led to nets being set and left
                                        unattended, often for several hours and even
                                        overnight. These rectangular nets – which are
generally 125 feet long by 7 feet deep and often sewn together to make much longer nets
of hundreds, even thousands, of feet – hang in the water like giant curtains.

Indiscriminate and Wasted Catches

         Lay gill nets have caused the depletion of coral reef fishes in many areas of the
  Cobb 1901 and CML DAR data compiled by W.J. Walsh, Hawai‘i Division of Aquatic Resources.
  Friedlander, A.M. and J.D. Parrish. 1997. Fisheries harvest and standing stock in a Hawaiian bay. Fish.
Res. 32:33-50.
  Birkeland, C. and A.M. Friedlander. 2002.
  Personal communication, Dennis Kawaharada. 06/2006.

Main Hawaiian Islands.9 By entangling many fishes at
once, and sometimes catching and drowning protected
species such as sea turtles and Hawaiian monk seals,10
the nets have proved to be devastatingly efficient and
indiscriminate. Lay gill nets often kill species of fishes
that the fisherman is not seeking. These may include the
young of species that would be of value if they had been
allowed to grow to commercial size, or fishes that are
valuable as prey to the targeted species.                               Green turtle entangled in a gill
                                                                        net set off the Wai‘anae coast.
                                                                        This one freed itself, but most
            Lay gill nets often kill fishes that are undersize by       that are caught in gill nets
                                             law. If the                drown. February, 2006.
     In Hawai‘i this spring, three           fisherman were to          Photo: John S. Johnson
     separate incidents resulted in gill     catch them by hook
     nets needlessly killing marine life,
     including more than a dozen             and line, he would release them. But in the gill net,
     hammerhead pups, a pregnant             they are dead or dying. Fishes left in a gill net for
     hammerhead, and a black tip shark. A    more than about 3 hours have started to decompose
     former     fisherman   and     native   and are discarded. Furthermore, fishes protected
     Hawaiian wrote to a local paper: “I'm
                                             during their spawning season can be caught by gill
     saddened by this waste of our ocean
     resources. In my lifetime, I've seen    nets, often more readily during spawning migration.
     the fish become fewer in number and     Lay gill nets that are lost, or that the fishermen are
     smaller in size... Our fish and our     unable to raise, continue to endlessly kill fishes.
     reefs have declined to the point that
     we cannot be selfish by continuing to
                                                 The nets also remove species that play a key
     use lay nets. Our ocean can no longer
     afford these careless ways.”       role in the health of the reef system. “Gill nets
                                        catch large quantities of herbivorous fishes” and in
  - Thomas Cummings, Jr.                Kāne‘ohe Bay, for example, “the reduced
  Honolulu Advertiser,                  abundance of this feeding guild may be
  June 16, 2006                         contributing to the current observed dominance of
                                        macroalgae.”11 Basically, over-harvesting of fish
that eat native algae results in unbalanced algae growth and declining reef health. When
moved from place to place, lay gill nets also become a vector for the spread of invasive
species, including invasive algae which further contributes to the decline in overall reef

       In Hawai‘i, gill nets are used by some 800 licensed commercial fishermen and
uncounted numbers of unlicensed fishermen.12 One study of Kāne‘ohe Bay estimated that
88 percent of the gill net catch there goes unreported.13 Hawai‘i state law currently

  Birkeland, C. and A.M. Friedlander. 2002.
   Clark, A.M. and D. Gulko, 1999. Hawaii’s state of the reefs report, 1998. Department of Land and
Natural Resources, Honolulu, Hawaii.
   Everson, A. and A.M. Friedlander. 2004.
   DeMello, J.K.. 2004. Commercial marine landings from fisheries on the coral reef ecosystem of the
Hawaiian Archipelago. In: Friedlander, A.M. Ed., Status of Hawaii’s coastal fisheries in the new
millennium. Proceedings of a symposium sponsored by the American Fisheries Society, Honolulu,
   Everson, A. and A.M. Friedlander. 2004.

requires that lay gill nets be left in the water for no more than four hours at a time and
inspected every two hours.14 But because of the dearth of enforcement officers, the law is
widely ignored and many nets are left untended for much longer periods.

Damage to Reefs

        If not set with care, lay gill nets can damage fish habitat. When removing them,
fishermen lift the weighted nets over reefs, and they can break off branch coral. While
those branches will grow back in ideal conditions, in the worst cases they can be
overgrown by algae, which prevents the coral from recovering. With surge, these nets
frequently get hung up on coral and are often abandoned because they are not so
expensive to replace. Abandoned gill nets can ‘ghost-fish’ for years. In 1998, officials of
the State of Hawai‘i gathered nearly five miles of net from coral reefs in Hawai‘i in a six-
month period .15 An entangled and abandoned net can cover and kill an entire coral
colony because algae grows where coral is abraded and on the net itself, which smothers
the reef area.
       In addition to the damage these lost nets cause to marine life, they also create an
unsightly mess on our shores and reefs and are a hazard to navigation because propellers
of boats may be caught in the nets. These nets are also dangerous for divers.

                                                                       In Fiji, a traditional chief
       The State of Hawai‘i Department of Land and                     described the nature of this
Natural Resources is proposing greater restrictions and                fishing method: “The gill net
                                                                       takes all the generations of
area bans on the use of lay gill nets. Restrictions already            fish: grandfather, grandmother,
appear to have met with success in Hilo Bay, where a gill              father, mother, and the children
net ban in 1987 resulted in increases in size of the main              fish, they all go into the net. It
species previously caught by gill nets: akule, manini,                 is not sustainable. Our
white ulua and āholehole.16                                            fisheries’ scientists have done
                                                                       the research and we have
                                                                       talked to fishermen, and it is
        Some Pacific Island nations, and all other coastal             clear that fish populations have
U.S. states, have restricted or banned the use of nets such            recovered faster because they
as these. Hawai‘i should be the first, not one of the last             are no longer being harvested
states to enact strong restrictions.                                   with gill nets.”

                                                                       - Paramount Chief
        The traditional chief in Macuata, Fiji – a province       Ratu Aisea Katonivere,
in north-central Vanua Levu – banned gill net fishing in          Fiji, June 2006
1988. The traditional fisherman, or gonedau, of the
province explains, “Our traditional fishing grounds are
not what they were when I started fishing 60 years ago, and I blame this on gill netting. I
used to gill net, and I know that it robbed us. It kills everything, what we eat and what we
   Title 13, Ch. 75, Hawai‘i Administrative Rules §13-75-12.
   Clark, A.M. and D. Gulko. 1999.
   Anonymous. 1992. An assessment of available information on the impact of gillnetting in state waters
and proposed measures to regulate the use of gillnets. Prepared by DLNR in response to House Concurrent
Resolution No. 421, House Draft 1. Sixteenth Legislature, 1992 Session. Honolulu, Hawai‘i.

do not eat. It made us poorer in every way you can think.”17 In Macuata, nets are now
allowed only on special occasions, such as important village functions. In a 1996 study,
gill nets were used experimentally and yields were compared to those recorded in the
early 1980s. The 1996 yields were found to be two times larger than those from the early
1980s. Mackerels and mullets, which had been nearly
wiped out of the area by the gill nets, were once again
abundant. Fijian fishermen, who have switched to
handline methods, said they “no longer need to travel
far to catch fish” and they “do not need to fish as long
as in the past to achieve good catches.”18 Fishermen
said they were quite satisfied with handline fishing
and did not advocate a return to gill netting.


       It is our recommendation that the State
                                                                       “Fortunately, we the people of
of Hawai‘i ban the use of lay gill nets, and                          Macuata realized what gillnetting
provide for effective enforcement to achieve                          was doing to our fishing grounds
this important objective.                                             and how that affected our daily
                                                                      living and source of income. So we
                                                                      decided to ban gillnetting almost 20
                                                                      years ago.”

                                                                      - Traditional Fisherman
                                                                      Fero Caba
                                                                      Fiji, June 2006

   Personal communication, traditional fisherman or gonedau of the Tui Macuata, the paramount chief of
the Macuata, Fiji. 06/2006.
   Ledua, E.S., S. Matoto, S. Sesewa, Y. Siassi, I.D. Raj, J. Korovulavula, P. Dalzell, and T. J.H.. Adams.
1996. Management of coastal fisheries in Macuata and Bua provinces, Vanua Levu, Fiji. South Pacific
Commission, Nouméa, New Caledonia.

John E. Randall, Ph.D.                                   Charles Birkeland, Ph.D.
Senior Ichthyologist                                     Adjunct Associate Professor, Department of Zoology
Bishop Museum                                            Asst. Leader, Hawai‘i Cooperative Fishery Res. Unit
Honolulu, Hawai‘i                                        University of Hawai‘i at Mānoa
                                                         Honolulu, Hawai‘i
         Dr. Randall is
the     world's     leading                                        Dr. Birkeland has
authority on coral reef                                  studied coral reef ecology
fish taxonomy. Born in                                   for more than thirty years at
Los Angeles in 1924, he                                  the Smithsonian Tropical
displayed an early interest                              Research Institute and the
in the sea and fishes.                                   University of Guam Marine
Upon graduating from                                     Laboratory. He has authored
UCLA in 1950, and                                        a book on the crown-of-
earning a Phi Beta Kappa key, Randall sailed his 12-     thorns starfish as a major
meter ketch to Hawai‘i to pursue doctoral research on    management problem for coral reefs, and edited the
surgeonfishes at the University of Hawai‘i. In the       1997 book Life and Death of Coral Reefs. He was
early part of his career, Randall performed field        also the third president of the International Society of
research in Tahiti, served at the Marine Laboratory of   Reef Studies. Throughout his career, Dr. Birkeland
the University of Miami, directed a three-year marine    has focused on coral reef communities, aspects of
biological study of the Virgin Islands National Park     reef recovery and resilience, and how to best manage
on St. John, and spent four years at the University of   these resources. His present research is directed at
Puerto Rico as a professor of zoology and director of    the biological characteristics and life histories of
the Institute of Marine Biology. He returned to          coral reef species, as well as the nature of ecosystem
Hawai‘i in 1965 as Director of the Oceanic Institute.    processes of coral reefs to examine whether marine
From 1967-1969 he held half-time positions at the        protected areas affect these various processes such as
Hawai‘i Institute of Marine Biology of the University    coral recruitment and fisheries yield.
of Hawai‘i and the Bishop Museum. He has served
as a member of the Graduate Faculty in Zoology of        Randall Kosaki, Ph.D.
the University of Hawai‘i since 1983. Dr. Randall is a   Research Coordinator
Distinguished Fellow of the Society of Ichthyologists    Northwestern Hawaiian Islands
and Herpetologists.                                       Marine National Monument, NOAA
                                                         Honolulu, Hawai‘i
Richard L. Pyle, Ph.D.
Associate Zoologist                                      Dr. Kosaki is a lifelong
Bishop Museum                                            fisherman. His academic and
Honolulu, Hawai‘i                                        professional background is in
                                                         the behavioral ecology of coral
Dr. Pyle spends much of                                  reef fishes, but his interests
his time exploring deep                                  and publications also include
coral      reefs      using                              biogeography, fish taxonomy,
advanced             diving                              and captive husbandry of
technology.      He     has                              marine fishes. His current
discovered more than 100                                 position involves the development and coordination
new species of fishes at                                 of monitoring efforts in the Northwestern Hawaiian
various           localities                             Islands (NWHI), as well as coordinating research into
throughout the Pacific,                                  ecosystem function to benefit natural resource
where he has traveled extensively on scientific          management there. Dr. Kosaki’s first trip to the
research expeditions. Born and raised in Hawai‘i,        NWHI was in 1982, and he has since sailed to those
Pyle did his doctoral studies at the University of       reefs on a variety of vessels, including the Polynesian
Hawai‘i and has worked in the fish collection of the     voyaging canoe Hokule‘a. Kosaki completed his
Bishop Museum since 1986. Determined to make             doctorate in zoology at the University of Hawai‘i,
deep-reef exploration safer for divers, Dr. Pyle was     and has taught marine biology and ichthyology at the
among the pioneers of modern Technical Diving in         University of Hawai‘i at Hilo.
the late 1980s and has been an active test-diver for
the prototype closed-circuit rebreathers ever since.


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