Marine Protected Areas,
14 Marine Protected Areas,
Fish and Fisheries
NICHOLAS V.C. POLUNIN
Chapter 14
300 is necessary to look at the evidence for such effects. This may allow patterns to be discerned in the
14.2.1 Abundance and body size
of target species
Drawing on data from underwater visual surveys umber of MP N 100
and on fishery catch-per-unit-effort (CPUE) data, and including the case of the North Sea where
50 entire grounds were closed during the First and Second World Wars, evidence for greater abun-
0 dances in MPAs than in unprotected areas is now 10 1000
available for a range of resource species in more Area (ha)
than 40 locations around the world, but there are significant spatial patterns in this evidence (Table
Fig. 14.1 Size distribution of 991 MPAs around the 14.1). For example, evidence for fishes derives world for which area is known. (Source: after Kelleher
et al. 1995, p. 14.) almost exclusively from underwater visual census
work on site-attached species on reefs in the Caribbean, western Mediterranean, Kenya, South Africa, the Philippines, New Zealand and New
One of the main objectives of this chapter is to Caledonia. Jones et al. (Chapter 16, Volume 1) have review the known impacts of MPAs with respect to noted differences in census techniques between fish conservation and fisheries management objec- temperate and tropical reef areas, and noted that tives, and help to characterize where, and if so these hamper comparisons of community ecology how, MPAs may be expected to contribute to the between these habitats. An exception is the evi- achievement of such objectives. I will also relate dence from the North Sea, where information MPAs to broader issues of environmental manage- came from catch and market statistics and the ment, including the uses of coastal waters by area protected spanned complete stocks and the tourists, participatory conservation and the main- duration of both world wars (Borley et al. 1923; tenance of biodiversity.
Margetts and Holt 1948). Otherwise, the lack of information on the effects of MPAs or fish abun- dance from South America, West Africa, South
14.2 WHAT HAPPENS TO
Asia and the Far East is a prominent feature; one
TARGET SPECIES IN MPAs?
of the North America East Coast studies is a fish- ing-based investigation of reef fishes in Florida,
Fishing is an additional source of mortality, and re- while the other two are equivocal and are complex duces survivorship of target organisms. Thus the assessments of large-scale closures (Table 14.1). principal direct effects of exploitation are reduc-
In a meta-analysis of 12 MPAs, selected on the tions in abundance, age and size. Accordingly, basis of full reporting of relevant data, Mosquera increases in mean numerical abundance, size, et al. (2000) showed that an overall positive effect age and biomass, of target species depleted by fish- of protection is discernible in the abundance of ing are expected particularly in MPAs. These fishery target species but not in that of non- effects are not assured. They may be mitigated target species. Where many species have been in- by a number of factors and processes, including vestigated, increase in abundance of target species mobility and spatial variability of recruitment at in MPAs has not been detected in all cases (Table large scales relative to the size of MPAs, so that it
14.1). Species other than fishes which have been
Table 14.1 Changes (increase, or * = no increase, _ = increase in some species, not others, – = no information) in abundance of various marine fishery target species in areas closed to fishing, or otherwise very lightly fished, in different parts of the world.
W. South
Australasia South America America
E. South
Caribbean
W. North
E. North
South Southeast East
Pacific Fish
Africa Africa
– – Marine Protected Areas 1. Russ 1985, Alcala 1988, White 1988, Alcala and Russ 1990, Russ and Alcala 1996.
21. Munro 1999.
2. McClanahan and Shafir 1990, Samoilys 1988.
22. Wantiez et al. 1997.
3. Clark et al. 1989.
23. Wallace 1998.
4. Bell 1983.
24. García-Rubies and Zabala 1990.
5. McCormick and Choat 1987, Cole et al. 1990, Babcock et al. 1999.
25. Polunin and Roberts 1993.
6. Buxton and Smale 1989. 26. Algae: Castilla & Bustamante 1989. 7. Bennett and Attwood 1991.
27. Stoner and Ray 1996.
8. Davis 1977, Davis and Dodrill 1980, 1989.
28. Francour 1991.
9. Cole et al. 1990.
29. Pipitone et al. 2000.
10. Bowen and Hancock 1985.
30. Roberts and Polunin 1992.
11. Leary 1985, Klima et al. 1986, Roberts 1986. 31. Borley et al. 1923, Margetts and Holt 1948. 12. Yamasaki and Kuwahara 1990.
32. Rakitin and Kramer 1996, Chapman and Kramer 1999. 13. Weil and Laughlin 1984.
33. Polunin 1999.
14. Heslinga et al. 1984.
34. Polunin and Williams 1999.
15. Castilla and Durán 1985, Moreno et al. 1984, Castilla and Fernandez 1998.
35. Funicelli et al. 1988.
16. Lasiak and Dye 1989.
36. Hockey and Bosman 1986.
17. Rice et al. 1989.
37. Smith and Berkes 1991.
18. McCay 1988.
38. Fogarty and Murawski 1998.
19. Tegner 1989, 1992.
39. Armstrong et al. 1993.
20. Shepherd 1990.
40. Edgar and Barrett 1999.
Chapter 14
found to be more abundant in MPAs than unpro- egg production to be raised. In tropical snappers tected areas include muricid gastropods, abalone, (Lutjanidae), spawning may be more frequent and limpets, lobsters, sea urchins and kelp, where these occur over a longer period in larger than in smaller are exploited; these are from reef habitats. The animals (Grimes 1987), but more data are needed overwhelming evidence is that greater abundances to underpin the supposition that greater fecundi- develop in MPAs when site-attached species in the ties give rise to a greater total egg production in area have been substantially depleted by fishing.
MPAs than in unprotected areas. It is reasonable to Evidence for greater average sizes of target expect that in site-attached species which do not species in MPAs than in unprotected areas comes become more vulnerable to fishing through move- almost entirely from the study of site-attached reef ment out of protected areas, depleted local popula- fishes investigated by underwater visual census; tions in MPAs will support substantial increases in many of the studies are the same as those which egg production. have demonstrated abundance effects (Table 14.2).
In both reef fish population ecology and fisheries For reef fishes, the evidence is from work in population dynamics, the relationship between the Caribbean, Florida, the Mediterranean, Kenya, any increased egg output and actual recruit- South Africa, the Philippines, New Zealand and ment is uncertain (e.g. Sale 1991; Myers and Australia. Several target invertebrate species have Barrowman 1996; Myers, Chapter 6, Volume 1; also been found to be larger in size within MPAs Jones et al., Chapter 16, Volume 1). The scientific (Table 14.2), and these are again associated with basis for such uncertainty varies between the two reef habitat.
fields; to workers on reef fishes, recruitment refers to the supply of settlers from the plankton (though
14.2.2 Fecundity, recruitment and
see Hixon 1996) and is measured at very small spa-
movement of target species tial scales, while to fisheries scientists it is the
abundance of fish of a size large enough to be fished Increase in fecundity with body size is expected to and measured from large-scale fisheries data (e.g. occur in fish and other fishery organisms (Duarte Hilborn and Walters 1992; Myers, Chapter 6, and Alcaraz 1989; Elgar 1990). Given the variabil- Volume 1). Much of the evidence has supported ity of fecundity data and the lesser increase in fe- the origin of recruitment variability lying in the cundity with size in some species (Wootton 1990; egg and larval stages, which in fishes are rarely of Sadovy 1996), population fecundity will not in- less than two weeks’ duration (e.g. Brothers et al. crease appreciably in all species within MPAs, but 1983; Houde 1987; Thresher and Brothers 1989). It greater total fecundities of site-attached fishes has been inferred that in reef fishes, and most prob- should occur in MPAs than in unprotected areas. ably all marine fishes, recruits travel distances There will, of course, be exceptions.
from spawning sites that are commonly 25–50 The rate at which population fecundity can be times greater than the small spatial scales of most expected to increase will depend upon the rate of MPAs (Fig. 14.1). These distances may be modulat- growth and mortality and the relationship be-
ed by current patterns that will vary greatly over tween fecundity and body size (Sadovy 1996). Be- time. For particular localities, species and seasons cause greatly increased survivorship within MPAs there may be a high likelihood of small-scale local is likely, species so protected should attain maxi- retention of larvae, settlers and recruits (Jones et mal population fecundities within five years or so. al. 1999; Swearer et al. 1999). The extent to which Slower-growing species may take 10–20 years to do increased egg output rates from MPAs will lead to this (Polunin 1997).
greater abundances of late juvenile and adult reef If maximal population fecundities are to pro- fishes within particular MPAs remains an open duce a greater egg output rate by the stocks of question. A major reason for this is that the dy- females within MPAs then spawning must be namics of larvae and new settlers are little known. frequent enough in the larger individuals for the In marine animals that do not possess larvae, or
Table 14.2 Changes in average size (increase, * = no change, _ = increase in some cases, not others, – = no information) of various marine fishery target species in areas closed to fishing in different parts of the world.
Australasia South America America
W. South
E. South
Caribbean
W. North
E. North
Western
Southern West
East
South Southeast East
Pacific Fish
Africa Africa
– – Marine Protected Areas Other
– – 1. Russ 1985, Alcala 1988, Alcala and Russ 1990.
18. Beinssen 1989a.
2. Bell 1983, Francour 1991.
19. Wantiez et al. 1997.
3. McCormick and Choat 1987, Cole et al. 1990, Babcock et al. 1999.
20. Wallace 1998.
4. Buxton and Smale 1989.
21. Polunin and Roberts 1993.
5. Bennett and Attwood 1991.
22. García-Rubies and Zabala 1990.
6. Davis 1977.
23. Ferreira and Russ 1995.
7. Klima et al. 1986, Roberts 1986.
24. Algae: Castilla and Bustamante 1989.
8. Yamasaki and Kuwahara 1990.
25. Roberts and Polunin 1992.
9. Weil and Laughlin 1984.
26. Borley et al. 1923, Margetts and Holt 1948.
10. Heslinga et al. 1984.
27. Rakitin and Kramer 1996.
11. Castilla and Durán 1985, Moreno et al. 1984, Castilla and Fernandez 1998.
28. Polunin and Williams 1999.
12. Lasiak and Dye 1989.
29. Funicelli et al. 1988.
13. Rice et al. 1989.
30. Hockey and Bosman 1986.
14. McCay 1988.
31. Chapman and Kramer 1999.
15. Shepherd 1990.
32. Fogarty and Murawski 1998.
16. Ayling and Ayling 1986.
33. Edgar and Barrett 1999.
17. McClanahan and Muthiga 1988.
Chapter 14
have very short egg and larval stages, build-up of spawning stock biomass in an MPA may well lead to greater recruitment in the MPA, but in fisheries such cases are rare (e.g. Carr and Reed 1993; Allison et al. 1998). In the Discovery Bay Fishery Reserve, Jamaica, where target species have been severely fished down, nearly all the larval settle- ment was by species with extended pelagic phases (Munro and Watson 1999). In areas lacking such stock depletion, local recruitment which is less reliant on the vagaries of larval and early post- settlement life is a possibility. It is possible to say, that in areas with extensive and severe depletion, the scope for local recruitment will have been sub- stantially lost. It must be said that, larval supply is not the only process governing the abundance of animals of exploitable size; for example, abun- dance of juvenile gruntfish (Haemulidae) has been found to be lower within the Barbados Marine Re- serve than outside it and this is attributable to the greater density of piscivorous fishes as a result of protection (Tupper and Juanes 1999).
The spatial scale of the movement of species that are targeted by a fishery will clearly influence the likelihood that abundance will increase in MPAs (Kramer and Chapman 1999). In the reef- associated species which thus far have best exhib- ited abundance and size increases in MPAs, home- ranging and territorial behaviour appear to be very common. The spatial scale of routine movement is indicated by home range and territory size, and this is expected to increase exponentially with in- crease in body length. An indication of the positive relationship between mean home range area and mean fork length for 15 reef fish species is given by Kramer and Chapman (1999). There seem to be no data on how home range area might vary with size within important target species, such as the snap- pers (Lutjanidae) and groupers (Serranidae) of tropi- cal reefs. It is reasonable to suppose on energetic grounds that as body size increases in MPAs, so fish will tend to range over greater distances. Among species in temperate waters, the plaice Pleuronectes platessa exhibits a linear relation- ship between migration distance and body length in Dutch waters (Rijnsdorp and Pastoors 1995). This means that the probability of movement can
be expected to increase as body size of depleted target species increases in MPAs. For territorial species in MPAs of given sizes, it will be possible for individuals to move across boundaries into similar habitat where there is fishing. Movement may, however, be curtailed by habitat discontinu- ities; in the case of reef fishes, reef edges and open sand constitute such barriers to movement. Such discontinuities should therefore help promote biomass accumulation in MPAs (Kramer and Chapman 1999).