The scientific literature and reports provide various definitions of a marine protected area (MPA). The most updated and relevant version is as follows: “
MPAs that are designed to protect nursery habitats generally favor the survival of settlers and juveniles (Planes et al. 2000). Well-designed and managed MPAs benefit adjacent areas through a spillover effect, in addition to benefiting the conservation of fish assemblages in NTZs (Di Lorenzo et al. 2016). Spillover has positive effects on exploitable fish communities (Stobart et al. 2009).
The spillover effect of MPAs was proven by many studies. Population replenishment is determined by the existence of juveniles, which occur densely in shallow areas where anthropogenic impacts are concentrated (Cuadros et al. 2017). Once the juvenile period is over, survivors begin to move from nursery areas to adult habitats (Macpherson, 1998). With regard to this issue, Abecasis et al. (2009) found evidence of spatial movement of
On the other hand, some MPAs are declared as no-take marine reserves (NTRs) with total fishing restrictions (Mesnildrey et al. 2013; Rolim et al. 2019) and are very important areas for the preservation of marine resources (Halpern et al. 2009). In this context, Aburto-Oropeza et al. (2011) observed a large recovery of biomass in one of the NTRs and a consequent increase in total fish biomass (+ 463%) 14 years after the establishment of the no-take area; specifically, carnivores and top predators increased four and 11 times, respectively. The increase in fish biomass is associated with a combination of social (enforcement, social cohesion, and community leadership) and ecological factors, which can result in significant economic benefits and spillover effects.
The total number of MPAs and OECMs (other effective area-based conservation measures) has reached 1231, corresponding to a total surface area of 179.798 km2 (7.14% of the total Mediterranean area). Moreover, while in 2010 NTZs covered only 202 km2, i.e. 0.01% of the total Mediterranean surface area (GEF 2010), in 2016 their area reached 976 km2, i.e. 0.04% of the Mediterranean (MedPAN & UNEP-MAP-SPA/RAC 2017).
The Muğla Province (south-western Turkey) has the longest coastline (≈ 1500 km; Figure 1) in Turkey (Governorship of Muğla, 2019). There are many indentations in the coastline and these areas have become a shelter for many marine species. Gökova Bay is a gateway between the Mediterranean Sea and the Aegean Sea. Therefore, this valuable area is unique for the coast of Turkey. Kıraç & Veryeri (2010) mentioned that there are 352 fish species in the Gökova Bay MPA and they represent almost 73% of all fish species in Turkey (24 of them are threatened). On the other hand, many Lessepsian fish inhabit the Gökova Bay habitats (Ateş et al. 2017).
Gökova MPAs were declared as six different NTZs (Akyaka, Çamlı, Akbük, Boncuk-Karaca, İngiliz Limanı, Bördübet; 23 km2) on the southeastern coast of the Aegean Sea in 2010 (Bann & Başak, 2011). However, with the 2012 and 2016 regulations, the total number of shore angling areas increased to four in these six NTZs (GDFA 2012; GDFA 2016).
The sampling site, the Akyaka MPA, includes two fishery cooperatives: Akyaka and Akçapınar. Sixty families in Akyaka and 70% of the Akçapınar population rely on small-scale traditional fisheries for their livelihood (Bann & Başak 2011). Small-scale traditional fishery operations are conducted outside the NTZs. Native and Lessepsian species, especially
Prior to the establishment of MPAs, commercial fishers were the primary stakeholders in these areas. However, following the establishment of the MPAs, the use of these areas by recreational anglers, rather than commercial fishermen, may potentially have a negative impact on both sustaining fish populations and commercial catch. This impact becomes apparent when juvenile fish are harvested and is even more pronounced when the total number of recreational fishermen on the shore is considered and a simple projection is applied. The harvesting of juvenile fish in MPAs logically harms ecological and fisheries sustainability. It may have a knock-on effect that leads to fewer juveniles, less recruitment, less food for predators (Connel 1998), less catch (FAO 2000), less economic contribution to local fisheries (Dar et al. 2015), and overcapitalization in local fisheries (i.e. profit < capital; FAO 1999; Clark 1977). These negative effects contradict the objectives of MPAs. The issues addressed in this study are indicative of general problems in MPAs. On the other hand, the presence of a lagoon in the study area means that this area is of particular importance.
This study addresses shore angling, which is assumed to compromise MPA objectives. The analysis of the issue was supported by biological data. The annual catch per recreational angler was determined, as well as its direct damage to an MPA and indirect effects on commercial fishers were presented. The purpose of this study is therefore twofold. First, it emphasizes the importance of collecting and interpreting biological data to gain knowledge about MPAs and to understand how stakeholders may be affected by a proposed management plan. Second, the potential harm of recreational anglers in NTZs to small-scale commercial fisheries was assessed.
The methodology and results of the study can be used to understand the current situation in similar MPAs, as obtaining data on recreational fishing is often a challenge. According to the results of this study, based on the biological data from the MPA, some recommendations for fishery management authorities were proposed and interpretations for recreational angling catch in the light of conservation were provided.
The study was conducted between August 2016 and July 2017 in the Akyaka MPA, in the southwestern part of Turkey (Figure 1). The Akyaka MPA is located on the eastern side of Gökova Bay, which includes a lagoon area. The shore is mostly rocky and this feature makes the Gökova shore a sheltered area for juveniles of most species. On the other hand, in terms of fisheries, longlines, trammel nets and gillnets are commonly used in Gökova Bay (Ceyhan et al. 2009; Dereli et al. 2015). Gökova Bay is also a favorite fishing area for recreational fishers. Handline, demersal and pelagic jigs are prevalent techniques among recreational anglers.
Samples were collected monthly (two days on mid-month weekends; 12 months in total). The largest number of angler visits was observed on weekends. Therefore, the time and day of sampling were selected accordingly. The daily number of anglers was recorded for each sampling day. The sampling area has estuary characteristics. Most anglers perform on rocky and sandy substrates. Fishing tackle was designed according to the angling gear of other local daily anglers (i.e. anglers were mimicked; Fig. 2). Breadcrumbs were used as bait. Each sampling event started 3 h before sunset and was completed within 2 h. Sampling depths ranged from 1 and 3 m.
Captured individuals were brought to the laboratory in ice and identified to the species level. Total length was measured to the nearest 0.1 cm and weight was determined to the nearest 0.01 g.
Daily CPUE (kg angler−1 day−1) was determined according to the following formula (Aydın 2011):
Species caught were also categorized into commercial and non-commercial. Length at first maturity of each species (Lm or L50) was obtained from scientific papers on a given species (Supplementary Table S1) and total lengths were compared with length at first maturity and minimum landing sizes (MLS) for commercial species. According to the Turkish Commercial Fishery Communique, four of the commercial species caught have length restrictions:
Ricker’s (1975) formula was used to estimate the weight of all individuals that corresponds to at/after Lm and MLS:
Length–weight relationship estimates were performed in Microsoft Excel (Microsoft Corporation 2018) and RStudio was used for visualization (RStudio Team 2015).
A total of 24 angling operations were conducted during the study. The number of anglers varied depending on the season. While the number of anglers dropped to three anglers per day in winter, it reached up to 50 anglers per day in summer. The average daily number of anglers was determined to be 25 (± 13 angler) per day.
A total of 22 fish species (n = 487) belonging to 10 families were captured. Evaluation of each species was based on weight and abundance.
Ratios of species in the angling catch in the Akyaka MPA
Family | Species | Weight (g) | Number (n) | Weight (%) | Number (%) | Importance |
---|---|---|---|---|---|---|
Balistidae | 25.37 | 1 | 0.32 | 0.21 | C | |
Blennidae | 102.43 | 6 | 1.30 | 1.23 | NC | |
Gobiidae | 27.61 | 5 | 0.35 | 1.03 | NC | |
Labridae | 50.6 | 3 | 0.64 | 0.62 | NC | |
95.16 | 3 | 1.21 | 0.62 | NC | ||
Pomacentridae | 1449.76 | 146 | 18.42 | 29.98 | NC | |
Serranidae | 96.95 | 2 | 1.23 | 0.41 | C | |
Siganidae | 88.17 | 4 | 1.12 | 0.82 | C | |
2462.71 | 94 | 31.29 | 19.30 | C | ||
255.46 | 29 | 3.25 | 5.95 | C | ||
92.81 | 1 | 1.18 | 0.21 | C | ||
203.68 | 11 | 2.59 | 2.26 | C | ||
1100.58 | 86 | 13.98 | 17.66 | C | ||
Sparidae | 153.29 | 12 | 1.95 | 2.46 | C | |
84.96 | 4 | 1.08 | 0.82 | C | ||
266.52 | 18 | 3.39 | 3.70 | C | ||
31.36 | 1 | 0.40 | 0.21 | C | ||
890.36 | 48 | 11.31 | 9.86 | C | ||
Scorpaenidae | 6.95 | 1 | 0.09 | 0.21 | C | |
54.09 | 1 | 0.69 | 0.21 | NC | ||
Tetraodontidae | 290.94 | 10 | 3.70 | 2.05 | NC | |
42.02 | 1 | 0.53 | 0.21 | NC | ||
Total | 7871.78 | 487 |
C – commercial
NC – non-commercial
CPUE in recreational angling in the MPA
Total catch estimation | Catch (kg) | |
---|---|---|
Daily (1 angler) | 0.328 kg | 0.3 |
One weekend (1 angler) | 0.328 kg × 2 days | 0.7 |
All weekends in a year (1 angler) | 0.328 kg × 2 days × 52 weeks | 34.1 |
3 anglers (min.) | 0.328 kg × 2 days × 52 weeks × 3 anglers | 102.3 |
25 anglers in a year (mean) | 0.328 kg × 2 days × 52 weeks × 25 anglers | 852.8 |
50 anglers (max) | 0.328 kg × 2 days × 52 weeks × 50 anglers | 1705.6 |
The projection of future landings of
Results of non-linear regression for
N | Lmin.–L max(cm) | Wmin.–Wmax (g) | CI of | CI of | S.E. of | ||
---|---|---|---|---|---|---|---|
12 | 6.3–13.0 | 4.04–37.42 | 0.0131 | 3.10 | 0.0068–0.0239 | 2.86–3.37 | 0.115 |
Gökova Bay provides sheltered areas for many species. These areas have great potential for commercial contribution to local small-scale fisheries. However, recreational angling may have some negative impacts on small-scale fisheries, especially on target species and fish sizes. A total of 22 fish species belonging to 10 families were identified and many of the fish caught were smaller than length at first maturity and the landing projection showed that the total weight of the catch by recreational angling reached a significant value in the Akyaka MPA. The results of the study are discussed below under the following headings: size composition, landing projection, other examples of recreational fishing in different MPAs, spillover effect, catch-and-release fishing.
According to the results of the study, the maximum lengths of most of the species were below maturity lengths or minimum landing sizes (Supplementary Table S1). The presence of juveniles in the catch contradicts the ecosystem-based fisheries management. Harvesting unprotected immature individuals in their early life stages may prevent the spillover of species to exploitable legal fishery grounds. Therefore, recreational angling may have a negative impact on the sustainability of local stocks.
Many Sparidae species inhabit lagoon areas (e.g.
A total of 12 individuals of
Projection of length–weight relationships in
Catch | Landing Projection | ||||
---|---|---|---|---|---|
After maturation | After Minimum Landing Size | ||||
TL1 (cm) | W1 (g) | TL2 (cm) (TL1 + 6.7 cm) | W2 (g) | TL3 (cm) (TL1 + 11.7 cm) | W3 (g) |
6.3 | 4.04 | 13 | 37.51 | 18 | 102.95 |
6.6 | 4.64 | 13.3 | 40.26 | 18.3 | 108.37 |
6.9 | 4.82 | 13.6 | 43.14 | 18.6 | 113.98 |
7.2 | 5.88 | 13.9 | 46.16 | 18.9 | 119.78 |
7.4 | 6.57 | 14.1 | 48.26 | 19.1 | 123.76 |
7.6 | 7.61 | 14.3 | 50.41 | 19.3 | 127.83 |
7.8 | 8.07 | 14.5 | 52.63 | 19.5 | 131.98 |
8.4 | 9.12 | 15.1 | 59.69 | 20.1 | 144.99 |
9.1 | 11.94 | 15.8 | 68.70 | 20.8 | 161.24 |
11.5 | 28.21 | 18.2 | 106.54 | 23.2 | 226.28 |
11.7 | 24.97 | 18.4 | 110.22 | 23.4 | 232.39 |
13 | 37.42 | 19.7 | 136.23 | 24.7 | 274.84 |
Total weight (g) | 153.29 | 799.75 | 1868.40 | ||
S.D. | 10.6 | 31.2 | 54.5 | ||
S.E. | 2.9 | 8.7 | 15.1 | ||
Catch (g) | |||||
1 angler/day | 6.4 | 33.3 | 77.8 | ||
1 angler/weekend | 12.8 | 66.6 | 155.7 | ||
1 angler/year | 664.3 | 3465.6 | 8096.4 | ||
3 anglers/year | 1992.8 | 10 396.7 | 24 289.1 | ||
25 anglers/year | 16 606.4 | 86 639.3 | 202 409.5 | ||
50 anglers/year | 33 212.8 | 173 278.6 | 404 818.9 |
TL1 – total length of individuals caught; TL2 – length at/after first maturity of individuals caught; TL3 – length at/after minimum landing size of individuals caught; W1 – total weight of individuals caught; W2 – estimated weight of individuals caught at/after length at first maturity; W3 – estimated weight of individuals caught at/after minimum landing size
The projection presented is exactly in line with Bohnsack’s (2000) statement: “
Positive effects of conservation measures can be clearly understood from some observational studies. According to Harrison et al. (2012), marine reserves directly support fish and fishers. Roberts & Hawkins (2000) found that there are eight different fishing types in the area adjacent to the De Hoop Marine Protected Area (South Africa), and the De Hoop reserve provides protection to over 60 exploited species. According to Halpern (2003), density, biomass, size, and diversity of carnivorous, herbivorous, and planktivorous fish, as well as of invertebrate feeders and invertebrates are higher inside the reserves than outside. If the Akyaka MPA is properly managed under the conservation objectives, the contribution of fish and other organisms to commercial fishing grounds could be higher than at present.
On the other hand, banning the towed gear in MPAs provides an opportunity to increase species biomass (Fisher & Frank 2002). However, permitting recreational angling does not comply with the area closure management approach (Schroeder & Love 2002). Gökova Bay has an advantage due to trawl and purse seine restrictions. These restrictions are sound implementations, but shore angling may impede the recovery of the MPA and spillover of species to fishery grounds. The indirect effect of recreational anglers on the spillover of species may only become apparent over a long period of time. Commercial fishers target a large percentage of species caught by recreational fishers, and recreational fishers affect the catch of commercial fishers and their income (Font et al. 2012).
Common findings on recreational angling pressure were presented in some related studies on MPAs or NTZs. According to Schroeder & Love (2002), the primary source of fishing mortality is recreational angling. In this context, Venturini et al. (2017) determined the impact of recreational angling on fish stocks. They revealed contradictions with the law and the minimum catch size (in terms of first reproduction size). The interesting finding in their study was that NTZs (where the spillover effect occurs) attracted anglers and the gross harvest of anglers in their study area accounted for 8% of the total yield of the small-scale fishery.
According to the Turkish amateur fishery communique, amateur fishery is defined as: “
No studies on spillover have been conducted in the Gökova MPAs. However, results of previous projects showed that the spillover effect may occur in the Akyaka MPA. The first biodiversity study in the Akyaka MPA was conducted in 2010 by the General Directorate of Fisheries and Aquaculture, Turkey. Turkey Ecological Research Society (EKAD, 2013) conducted a second biodiversity study in 2013 and found that there were more fish species in the Akyaka MPA than in other areas. It was observed that while the maximum lengths of five species (
Marine and freshwater species have similar mortality rates in catch-and-release fishing (CRF). Fish mortality rates in CRF are affected by hooking location, natural bait, deep hooking, use of “J” or circle hooks, water depth and temperature, playing and handling times. Regarding hook types, barbless hooks result in lower fish mortality than barbed hooks (Bartholomew & Bohnsack 2005). Aalbers et al. (2004) reported that all mortalities occurred within five days of release (i.e. released fish may have a low survival). Logically, the occurrence of release mortality is inconsistent with NTZ objectives (Bartholomew & Bohnsack 2005). As regards hook types and fishing gear manipulation, all recreational fishers in the Akyaka MPA use barbed hooks. Furthermore, it has been observed that some anglers do not use their hands in the process of removing fish from hooks, especially if they do not know what they caught, and instead they step on the fish with one foot to remove a hook and then release it. This manipulation may potentially significantly increase fish mortality. Therefore, CRF should not be considered a good option for shore angling in the Akyaka MPA. In this regard, lack of education among anglers was identified as the major shortfall. People need to be educated about marine life to ensure that mortality is reduced.
On the other hand, Sale et al. (2005) argued that too many MPAs are located in the wrong places. According to the present study, although the Akyaka MPA was established in the right place (i.e. near the lagoon), the presence of juveniles in the recreational catch indicates that this area is not properly managed. Partial protection may have benefits (like trawl restrictions for habitat protection), however, partially protected areas are not as effective as NTRs (Sala & Giakoumi 2018). More comprehensive protection plans should be put into effect.
In addition to all the above methods, lure fishing has also been observed in the Akyaka MPA. Anglers who use this method, target fish such as
Although recreational fishing is not a commercial activity (i.e. no fish are sold), it makes a significant economic contribution to other fisheries-related sectors (by spending money on food, bait, accommodation, travel, boat fuel, boat maintenance and fishing gear costs; Tunca et al. 2013). However, this economic contribution depends on sustainability of fish stocks (i.e. importance of juveniles).
Samples for the study were collected using simple fishing tackle that any angler can purchase. This easy access may lead to increased potential of recreational angling and may increase the pressure on juveniles. As mentioned in various studies on juveniles, the sustainability of fish stocks depends on recruitment success. In addition, negative effects of lost fishing gear that originates from recreational angling should not be ignored.
Therefore, the following conclusions can be made:
Juveniles should be protected and the spillover effect should not be prevented to ensure the spread of species to fishery grounds; this strategy may potentially have a large economic contribution to local fisheries in the future; Due to the presence of the lagoon and the harvesting of juveniles, recreational fishing should be completely banned on the shore of the Akyaka MPA; People should be educated to ensure awareness of catch-and-release fishing, stock–recruitment relationships and MPAs. In conclusion, allowing recreational anglers in MPAs does not comply with the conservation objectives of NTZs due to their potential negative impact on sustainability.