Mapping Seagrass Beds in Corner Inlet from the Memory of Local Professional Fishermen
A Project of National Landcare Innovation Program Project supported by the West Gippsland Catchment Management Authority, South Gippsland Landcare Network and the Corner Inlet Fisheries Habitat Association
The relationship between the health and distribution of seagrass and fishing has long been recognised by the commercial fishing industry.
In 1974 fishermen from the main basin of Corner Inlet were alarmed by the decline of Broadleaf seagrass beds and contacted scientists in NSW and Victoria. From this interaction fishermen learned about how this seagrass flowered and seeded and became diligent observers and watched as the Broadleaf seagrass beds made a partial recovery.
Since 1999 the Corner Inlet Fisheries Habitat Association, representing fishermen from all the ports, has taken every opportunity to express its concerns regarding the ongoing decline in seagrass, especially Broadleaf seagrass.
There have been a number of science based projects to map seagrass in the Inlet but these have either mapped all species ‘as one’ or used ariel photography to map changes in selected sites and then relied on ‘ground truthing’ from relatively brief visits to confirm which species were being mapped.
What was needed was a broad scale map of the current distribution of broadleaf and Fineleaf seagrass beds – the most persistent – across the entire basin which could be updated cost effectively. This broad scale mapping also needed to be done in a way that would enable the knowledge of older retired fishermen to be recorded.
With the support of the farming and fishing communities for mapping of seagrass from the fishermen’s collective memory this project was born.
The maps it generates are historical and indicative and not scientific and precise. However they enable fishermen, for the first time, to convey the changes in their ‘pasture’ to the adjacent rural community, government and corporate land managers. It will likely be their activities will have a significant bearing on the maintenance and restoration of seagrass beds.
Nature of the Corner Inlet, the Seagrass and Fishermen as Observers
In the ‘hook’ of Wilson’s Promontory Corner Inlet basin covers approximately 600 square kilometres at high tide. It has a tidal range of in excess of 3 metres (storm tides) and during the lowest tides most of the inlet is exposed.
The Inlet has supported a commercial fleet since the mid 1800’s with the many of the current families that fish the inlet established by the turn of last century.
The shallow tidal banks of the inlet, the myriad of channels that divide them and the various beds of seagrass, especially Broadleaf and Fineleaf seagrass make up these fishing grounds.
Knowledge of the distribution and state of seagrass beds is critical to successful fishing as is a memory of where it is and where it has been.
The dense beds of all species of seagrass provide shelter for a wide range of juvenile fish species from the waves, tidal currents ands from fish and bird predators.
The blades of seagrass provide a stable surface for a wide variety of tiny encrusting animals and other marine plants which in turn provide food for juvenile and adult fish.
The root mass of seagrass beds deliver oxygen to what are often otherwise black mud and sand devoid of life. In this rich layer live millions of shellfish and crabs etc. all food for fish and other predators including migratory wading birds
It is these characteristics that make seagrass beds that are most important to the recreational and commercial fishing industries and the huge range of species that live in and visit Corner Inlet. The declaration of Marine Reserves, Conservation Areas and Marine National Parks in Corner Inlet since 1984 has been in recognition of its rich diversity.
The Changes in the Dominant Seagrass Species
Fishermen have been concerned about the losses of Broadleaf seagrass beds since 1974 when the losses were so dramatic that some fishermen began land based businesses. Broadleaf seagrass beds have made a partial recovery on the banks closest to the entrance, where the Inlet opens to Bass Strait, but there has been a steady decline observed in the northern and western parts of Corner Inlet since that time.
Broadleaf seagrass beds in Victoria have only ever occurred in Corner Inlet. These beds go through predictable annual cycles their growth peaking in the warmer months with blades (leaves) up to 1.5 metres long breaking off through autumn. These broken blades form massive rolls on the banks of the Inlet and along the shoreline. This 'breakdown' of dead seagrass attracts vast numbers of invertebrates which in turn attract fish.
Broadleaf seagrass beds may decline rapidly but are slow to re-establish. Broadleaf seagrass grows from the intertidal zone and to a limited depth.
Fineleaf seagrass is common throughout Victoria’s Bays and Inlets but unlike Broadleaf seagrass it has no regular seasonality in its seeding or ‘break off’ and can also rapidly colonise areas. It also breaks off when it is green and apparently alive which raises the possibility or that broken stems may be able to regrow. Fineleaf seagrass grows in the subtidal zone and to depths of 20m or more and can be highly productive for commercial and recreational fisheries.
Swangrass is the finest leaved and smallest of the bed forming seagrasses. It can rapidly form beds on intertidal zones being able to withstand long periods of exposure at low tide. As the name suggests this seagrass is targeted by Black Swans that only graze it when it is underwater with large flocks following the tide for optimal grazing depth.
Like Fineleaf seagrass the seeding and spread and break off timing of swan grass is unpredictable. It is this seagrass however that has during the study period covered vast areas of Corner Inlet growing right up to the edges of the sandy beaches and across the banks first exposed by the falling tide.
In previous years the appearance of Swangrass has been erratic and it is unusual for it to persist across such a large area. Swangrass can also disappear from Corner Inlet and in the 1950’s its absence led to Black Swans moving onto farmland in huge numbers.
There are other seagrass species in Corner inlet but the do not form beds and were not mapped as part of this project.
Neither Fineleaf seagrass nor Swangrass invade Broadleaf seagrass beds; however Broadleaf Seagrass can invade both Swangrass and Fineleaf seagrass beds.
Methodology
Recording Information from Fishermen
Modern computer technology and software can greatly enhance the speed and reliability of recording data but it needs to be used wisely.
Fishermen, especially older fishermen were not at all comfortable, with recording their observations directly onto a computer screen using commercially available programs such as Corel Draw. There is also always the possibility of losing electronically recorded data.
It was decided that fishermen would be given lead pencils and maps to draw on and these maps would be digitally photographed.
Map Selection
There are many maps of Corner Inlet to chose from but the final selection was a map first drafted by A.H.Copplestone of the Foster Boat Club at a scale of 1 inch to the mile in 1970 and another from the Shire of South Gippsland drawn by M. Noonan in 1990 is also scaled at 1 inch to the mile.
Both maps have a freehand style and used fishermen’s knowledge to name most of the dozens of gutters that cross the banks of the inlet. The later map was used for the fishermen to draw on as it had more comprehensive drawing of gutters and banks (though through the process of mapping the seagrass distribution the location of some of the features, especially high ground known as ‘lumps’ was changed to better match what fishermen interviewed observed.
Interview Method
Failure of group mapping and recognising confidentiality
From the outset the first task of this project was to create a map current distribution of Seagrass from bringing all the fishermen together. Only two fishermen turned up despite written invitations – and they were the most recent entrants into the fishery.
The detailed knowledge of the distribution of seagrass is the key to successful fishing and needs to be treated in a far less cavalier fashion.
The project was quickly reorganised and the collection of data regarding the current distribution of was done with each of the fishermen who fished in the inlet individually and none of that individually generated data was shared with other fishermen.
There is no concern for the aggregated data being published some months after it has been collected – reflecting in part how rapidly the state of seagrass beds - and the fishing they generate - changes.
As there is considerable overlap between virtually all the areas fished in Corner Inlet the information from one fishermen was easily cross referenced against another when the ‘master map’ was compiled.
The Interviews
Equipment
Interview Method
Interviews were mostly conducted in fishermen’s homes with two conducted in a local café and two at the author’s home.
Bookings were made with fishermen and checked just prior to time of the booking.
Each interview was in regard to a single period whether it was the current distribution of seagrass or discreet year in the past.
For historic interviews the times chosen were of the greatest significance to the fishermen interviewed - when they first started fishing, when they came back after a break, around the time of local tragedy etc.
Sound Recording
All the fishermen were informed that they were being recorded while they were drawing the seagrass distribution to help with the interpretation of their drawing and to build up an historic context for their observations. From time to time some fishermen would ask for the recording to be turned off and at other times the interviews were interrupted and the recordings stopped and started.
Drawing Seagrass Distribution
15 -20 maps were taken to each interview in a roll. These maps were unrolled on a table and the Laptop computer used for sound recording Was used as a weight to hold usually the top edge of the map flat with other weights being what ever was to hand.
The Lap Top screen was on and showed the LIFFRAME recording software layout with a red light indicating the recorder was on.
Fishermen were given pencils, a rubber and a sharpener.
Early in the interviews Broadleaf grass was to be discerned by solid shading and Fineleaf beds by diagonal cross hatching. On occasions other distinctions were required such as that for sparse broadleaf and for seaweed nixing with Broadleaf and Fineleaf beds.
When channel names were added, the locations of high ground or ‘lumps’ was different to that shown on maps etc notes were made in the margins of the map with numbers often relating to the what was being referred to.
Each session took between 3 and 4 hours to create a map from a single period of time.
Only the location of Broadlleaf seagrass beds was recorded for ‘Historic Distribution’ Interviews.
Translating Drawn Seagrass Distributions to a Single Map
With no precedent for combining information collated in this way the task of translating all this information onto a single ‘Master Map’ was an onerous one. Several methods were tried and failed for either not reflecting the accuracy of the information provided or for being far to time consuming.
Ruth Lyon, a professional artist working in the film industry offered her services and expertise in translating shapes from one medium to another.
A large copy of the Foster Boat Club Map by A.H. Copplestsone was chosen as, though it did not include all the channels or the mapping gridline, it provided the best opportunity to translate the ‘shapes’ of the seagrass beds while still maintaining its integrity as a navigational map.
Creation of a ‘Master Map’
Each of the maps created by fishermen was photographed in natural light with a Cannon Pro1 8 Mega pixel Digital Camera. The images were downloaded onto the ASUS Lap Top and saved as JPEG images and saved in a Cannon Zoombrowser File and labelled with each fisherman’s name.
Using an NEC VT 491G Digital Projector these images were projected on a white wall beside and the same size as a master map. Another mount was made so the original maps could also be viewed at the same time.
Over 24 hours each map was analysed, viewed with portions of the recorded interviews played and notes from margins read to make it clear just what each fisherman was trying to draw.
A series of codes was designed to discern each of the varying types of seagrass habitat that was being mapped and these codes were added to each of the discreet shapes drawn.
Each of these codes also was allocated a colour or pattern and finally a colour painting with acrylic paint was made discerning the various states of broadleaf seagrass and Fineleaf seagrass distribution.
At each stage was checked against the fishermen generated maps, notes and recordings.
The 1st Draft Mater Map of Current Broadleaf and Fineleaf Seagrass Distribution
The production first draft map showed an amazing correlation between the maps sketched by fishermen – and the errors they discerned from the base map used.
The first draft ‘Master Map’ was printed and scanned and shown to commercial and recreational fishermen and residents living along the coast familiar with seagrass beds.
By scanning the map and then using Photoshop 7 software the colours used could be matched and preserved.
The comments from recreational fishermen and local residents were noted before revisiting key commercial fishermen to go over the map created area by area to add further information.
From this the final Master Map of the Broadleaf and Fineleaf Seagrass Distribution for Corner Inlet
Historical Seagrass Mapping
The historical mapping of the distribution of seagrasses has to date remained in the hand drawn form with backup digital images and recorded interviews while the mapping was undertaken.
The recorded interviews and historic Maps will be made available to the local Historical Museums and stored in the Regional Research Library
Public Presentations of the Seagrass Mapping Project
Sea Days
Every January the Ferry Terminal Building at Port Welshpool is the venue for the Sea Days Festival. Here the staff from the Marine National Park and the Fishing Industry conducted talks, excursions and hosted displays for the locals and tourists promoting the natural history of the Inlet’s seagrasses. Over the three days of the display talks illustrating the seagrass project and the wildlife associated with seagrass were given to compliment excursions and other activities.
Food and Fibre Field Day
Through the Future Food and fibre Project a day for fishermen and farmers to get together on Corner inlet was organised on the 7th of March 2008.
This was a hugely successful day with fishermen taking over twenty farmers out into Corner Inlet to view both healthy seagrass beds and the places where algae was smothering beds.
In the future it may be possible to track both the changes in seagrass beds and the changes in land management in the catchments feeding into the Inlet
For farmers it was a realisation that fishermen too depended on pastures - but pastures they had little control over. The fishermen showed their appreciation for revegetation of stream sides by farmers and discussed common issues over a feed of locally caught fish.
The 1st Draft of the Seagrass Map provided an accurate guide to the beds visited on the day.
Ongoing work from the Seagrass Mapping Project
Launch of Maps for Sale to Create Funds for Annual Mapping
Now that an electronic version of the current distribution of seagrass has been created it will be possible to update this map annually and track the changes in seagrass beds.
The Formal Launch of the Seagrass Maps
In the spring of 2008 there will be a Launch of various versions of the Seagrass Map designed to cater for key groups that use Corner Inlet.
The Map is particularly popular among Recreational Fishermen who regularly visit corner inlet from the Latrobe Valley, Cranbourne to the east coast of Port Phillip Bay and as far afield as the Kerang with the Kerang Fishing Club visiting Corner Inlet over many years.
The Marine National Park Managers run a series of excursions visiting Broadleaf seagrass beds in the Marine National Park on the south eastern tip of Corner Inlet, developing the local ecotourism industry. It is likely that there will be a demand for seagrass maps from the bed and breakfast, accommodation, caravan and camping sectors of the tourist industry.
For the Schools visiting corner inlet from the surrounding region there is also likely to be a demand for the maps, especially where they show access points to view the seagrass from the shoreline.
Additional Activities
Recreational fishermen liaison
Bears Bash 26/27th July
Local liaison
Morwell fishermen the Richer family and friends
Seawall fishermen
Patreson Road Fishermen
Foley road camping Ground Fishermen
Rec fishing groups and clubs
Lake Tyres meeting
Radio Show
23rd August
Consulting for design of poster