Coastal environments provide a wide range of leisure opportunities, including recreational fishing. Understanding spatial and temporal fishing patterns is important in ensuring wise management and sustainable use. To provide information on shore angler effort and distribution, randomised aerial surveys of the Garden Route coast between the eastern border of the Tsitsikamma Marine Protected Area and the Kaaimans River mouth in the west were undertaken between December 2008 and November 2009. A total of 15 flights were conducted, with six flights taking place over weekends, two on public holidays and the balance on normal week days. Angler effort was not uniformly distributed along the coastline, and spatial analysis highlighted coastal areas both inside and outside marine protected areas that had increased angler effort. In general, fishing effort was highest around more densely populated areas and concentrated in areas with easy access. Although angler counts were highly variable, the seasonality of shore angling effort showed a slight increase during autumn and winter and angling effort was significantly higher on weekends.
Coastal environments provide a wide range of recreational opportunities and are highly valued amongst various user groups (James
Recreational fishing is a popular activity and can arguably have a large impact through over-exploitation and harvesting of select species. Although it is unlikely that a single angler's catch can have a measurable impact on fish populations, the cumulative impacts of (1) the widespread nature of recreational angling, (2) the total number of anglers involved and (3) the defined habitats in which fishing occurs are important factors to consider (Cooke & Cowx
Within the South African shore-based linefishery, overfishing by recreational anglers is seen as a contributing factor to changes that have occurred in the composition of species catch (Bennett
The benefits of MPAs typically include the restoration of marine ecosystems and natural ecosystem functioning, increased species diversity, and natural size and age structure of protected fish populations (Halpern
During this study, aerial surveys, as an alternative method to traditional on-the-ground or water-based surveys (Brouwer
This study was conducted along the Garden Route coastline of South Africa between the Groot River in the east and the western border of the Kaaimans River mouth (
A map of South Africa showing the location of the study area along the south coast, and the location of marine protected areas, municipal wards and towns within the study area.
Population numbers per ward for each of the local municipalities within the study area.
Municipality | Municipal wards | |||||
---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | Other wards | |
Kou-Kamma | - | - | - | 6325 | 6902 | - |
Bitou | 8119 | - | - | - | 5974 | 23 485 |
Knysna | 6210 | 5793 | 4852 | - | - | 38 624 |
George | 9356 | - | - | 8192 | - | 129 253 |
Note: George ward 16 lay outside the study area and has not been included. Other wards include small, higher-density wards within the study site, generally close together and situated around town centres (Bitou wards include wards 2, 3, 4 and 6; Knysna wards include wards 4, 5 and 6–8; and George wards include wards 2, 3, 5 and 6–20).
Three MPAs are situated within the study area: The Tsitsikamma MPA consists of 68 km of closed (no resource use) coastline and forms part of the Garden Route National Park, managed by South African National Parks, whilst both the Robberg and Goukamma MPAs, managed by CapeNature, are open to shore angling, but no boat angling is permitted.
Monthly aerial surveys covering the survey area were conducted between December 2008 and November 2009 in order to obtain ‘instantaneous’ counts of shore angling effort. Survey days and flight times were randomly selected, but depended on the weather, and pilot and observer availability. All flights were conducted during daylight hours, with the earliest flight taking place at 09:10 and the latest at 15:55. All counts were done in an east–west direction, as the observers were seated on the starboard side of the plane.
The first four surveys were undertaken in a four-seater Robinson helicopter, after which a four-seater Cessna light aircraft was used. Flight parameters, including air speed and altitude, were standardised, but depended on weather conditions and the pilot's discretion. Flight times ranged between 70 min and 80 min, with an average air speed of 189 km.hr−1 for both aircraft. Altitude ranged between 30 m a.s.l. and 80 m a.s.l. for the Robinson and between 150 m a.s.l. and 250 m a.s.l. for the Cessna.
On each flight, two observers counted shore anglers and one scribe entered the data into a global positioning system-enabled pocket PC. Each spotter was equipped with a pair of binoculars (10 x 42 magnification) and continuously scanned the coastline, verifying the other spotter's counts. When large groups of anglers were encountered, a second flyby was made and anglers were re-counted by both spotters. Information recorded during the aerial surveys included the date, time, weather, sea conditions, number and location of anglers or boats and habitat where shore anglers were fishing (rock or sand).
Data were also obtained from three aerial surveys conducted in December 2008 as part of a study researching the ecology, value and management of the Garden Route (Chalmers et al.
The southern Cape coastline that falls within the study area was buffered by 1 km to create a polygon representing the area of interest. Spatial mapping of angler effort was plotted using three different coastal breaks. The first method (equal breaks) split the coastline into 10 km sections. The second method compared the status (MPA or non-MPA) using the layer of the MPAs of the National Spatial Biodiversity Assessment (Lombard et al.
Aerial survey point data containing angler counts were overlaid onto each coastal break layer and the density of anglers per coastal section for each of the different breaks was calculated as anglers.km−1. Angler effort was depicted in graduated colours for seven natural break classes. Kruskal–Wallis one-way analyses of variance (ANOVAs) were performed to determine if there was a difference in angling effort spatially for each of the three different coastal breaks, and temporally between week and weekend days and seasons.
The unit of fishing effort chosen was angler outings, with data pooled seasonally due to unequal sampling effort. Total seasonal fishing effort (Eseasonal outings) was calculated using the following formulae:
Where EW1 and EW2 are the weekday and weekend estimates respectively, given by:
Where
Total annual fishing effort (EToutings) was calculated as the sum of the estimated seasonal effort (Eseasonal outings) multiplied by a correction factor (2.48) to account for angler turnover.
Total annual fishing effort (EToutings) was then multiplied by the average fishing trip duration of anglers interviewed during two ground-based roving creel studies (Smith
A Kruskal–Wallis one-way ANOVA was performed to determine if there was a difference in angling effort between seasons, and a Mann–Whitney
A total of 15 aerial surveys were conducted between December 2008 and November 2009 (
Summary of aerial surveys conducted each month, grouped seasonally and stratified according to week or weekend day.
Day type | Summer | Autumn | Winter | Spring | |||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Dec.† | Jan. | Feb. | Mar. | Apr. | May | June | July | Aug. | Sept. | Nov. | |
Week | am | - | am | - | am | am | - | am | - | - | am |
- | - | am | - | - | - | - | - | - | - | - | |
Weekend | am | - | pm | pm | am | - | - | am | am | am | - |
am | - | - | - | - | - | - | pm | - | - | - |
Note: No aerial surveys could be conducted in June.
Angling effort showed a heterogeneous distribution throughout the study area and although variability in count data was high, a significant difference in angling effort occurred between MPAs and non-MPAs (Kruskal–Wallis one-way ANOVA,
The South African Garden Route coastal section broken into equal areas (A) and the spatial distribution of total angling effort (anglers.km−1) between Kaaimans River in the west and the eastern border of the Tsitsikamma Marine Protected Area at the Groot River (B). Up–down bars indicate the 95% confidence interval.
The South African Garden Route coastal section divided into marine protected areas and open areas (A) and the spatial distribution of total angling effort (anglers.km−1) within marine protected areas and open areas between the Kaaimans River in the west and the eastern border of the Tsitsikamma Marine Protected Area at the Groot River (B). Up–down bars indicate the 95% confidence interval.
The majority of anglers (72.50%) fished in open access areas outside formal conservation borders (including no-take and controlled zones) and a Bonferroni post-hoc test showed that the Tsitsikamma MPA had significantly less fishing effort than all other sections (
Outside of formal protected areas, the highest density of anglers occurred in section one (Wilderness) with 1.35 anglers.km−1, followed by section 15 (Plettenberg Bay) and 17 (Nature's Valley) with overall angler densities of 0.78 anglers.km−1 and 0.58 anglers.km−1 respectively (
Angling effort occurred on both rocky and sandy substrates throughout the study area with both high densities (2.23 anglers.km−1 – 3.94 anglers.km−1) occurring over rocky (
The distribution of total angling effort (anglers.km−1) between the Kaaimans River in the west and the western border of the no-take Tsitsikamma Marine Protected Area between rocky areas (A), sandy areas (B) and both rocky and sandy areas combined (C).
Although more anglers were encountered during the autumn (0.37 anglers.km−1) and winter (0.38 anglers.km−1) months (
Mean shore angling effort (anglers.km−1) (a) seasonally and (b) during week and weekend days along the South African Garden Route coast between December 2008 and November 2009 (public holiday counts were included as weekend days).
Total annual shore angling effort was estimated at 49 812 angler outings. Recent angler interviews conducted along portions of this coastline indicate that anglers spend on average between 5 hours (Smith
Assessing spatio-temporal resource use patterns is important when implementing fishery and conservation management practices. This information can help with future conservation and spatial planning exercises by highlighting areas from which anglers may be displaced or, conversely, areas where no fishing activity occurs and which may act as natural spatial harvest refugia for target species (Smallwood & Beckley
Angler distribution is unlikely to be uniformly distributed along any coastline and may be impacted by access points and infrastructure that have a clustering effect (Smallwood
Recreational fishing along the Garden Route coastline showed a heterogeneous spatial distribution, with some localised areas having high angler densities. These areas were generally associated with ease of access and proximity to the more heavily populated urban areas of George and Plettenberg Bay. A similar pattern was shown along the KwaZulu-Natal coast of South Africa (Mann et al.
In fisheries where angling effort is widely dispersed (e.g. coastlines), instantaneous estimates of total fishing effort obtained from aerial surveys are more accurate and preferable to land-based roving creel surveys (Pollock et al.
Greater angling effort (1.03 anglers.km−1) was recorded along the Wilderness to Sedgefield (Smith
The distribution and density of recreational users in general is known to be impacted by large temporal factors such as seasons and holiday periods (Hingham & Hinch
Two popular targeted shore angling species, galjoen (
Given that no previous aerial surveys have been conducted along the Garden Route coastline and shore-based surveys have only covered portions of the coastline, it is impossible to say whether total fishing effort is increasing or not. A decrease in shore-based angling effort along the KwaZulu-Natal coastline (Dunlop & Mann
With greater biodiversity and abundance of fish, MPAs where fishing is allowed are attractive locations for recreational anglers (Cooke et al.
Within the Ningaloo Marine Park in North West Australia, anglers were found to be concentrated in localised areas with easy access, and limited non-compliance was observed within no-take zones (Smallwood et al.
Although the Goukamma and Robberg MPAs are open to shore-based fishing, these areas had comparatively lower angler densities than other sections of coastline outside the formal conservation areas. Fishing locations within Robberg are limited due to a large seal colony on the eastern side and the exposed rocky coastline on the west, restricting fishing to a few well-known locations (King
Surveys to provide information on spatial and temporal patterns of resource use need to be designed and implemented at appropriate scales. Numerous access points, the longitudinal and rugged nature of coastlines and the size of management areas complicate survey design. Aerial surveys can be an effective technique for obtaining spatial and temporal data on recreational activities, including fishing, over a broad landscape (Pollock et al.
To avoid sampling biases, flights must be random in terms of direction, time of day and type of day (week or weekend) (Pollock et al.
Spatial accuracy of observed data points was improved through the use of data loggers that automatically recorded time and positional information, enabling the observers to simply record numbers and substrate. Prominent landmarks were also geo-referenced prior to the aerial flights, providing a known position that could be recorded, eliminating sampling errors associated with fishing at these points. However, visibility bias and in particular difficulty in seeing anglers on rocky sections of coastline may have led to an underestimation of total angling effort. Ground truthing of counts would be important for future surveys.
Aerial surveys are a useful and well-established method of collecting data across large spatial scales. These data can be used in both future planning exercises and also in determining the success of current management plans and policies (e.g. non-compliance with spatial zoning).
Although our ability to estimate total angler effort from the current data set is limited due to unequal monthly sampling effort, results from this study showed temporal trends with seasonal fluctuations for recreational fisheries. An increase in effort over weekends and public holidays was evident, whilst broad-scale spatial patterns were similar to results from more in-depth, land-based projects.
In general, fishing effort was highest around the more heavily populated areas of George and Plettenberg Bay and concentrated in areas with easy access. Should aerial surveys be implemented again, care should be taken to ensure equal monthly effort (i.e. flights should be conducted at least bi-monthly – on one weekday and one weekend day or public holiday), with flight scheduling incorporating back-up days for bad weather and mechanical problems. The value of surveys could be further increased by collecting data on other types of coastal resource use, such as bait harvesting.
The findings of this study have relevance to the management of the fishery along the Garden Route coastline in guiding the deployment of fisheries management field personnel, both spatially and temporally, to maximise contact with fishers and therefore improve levels of compliance.
Funding for the flights was made available through the National Marine Protected Area budget, allocated to the South African National Parks by the Department of Environmental Affairs. We thank the volunteers and pilots who assisted during the aerial surveys and two anonymous reviewers for their positive contributions towards this manuscript.
The authors declare that they have no financial or personal relationships which may have inappropriately influenced them in writing this article.
M.K.S.S. (South African National Parks) was responsible for the study conceptualisation, data collection, analyses, report writing and editing. N.K. (South African National Parks) contributed to the study design, data collection, GIS analyses, report writing and editing, and T.S.M. (South African Institute for Aquatic Biodiversity) contributed to the study design, data collection, report writing and editing.