Perceptions of environmental change over more than six decades in two groups of people interacting with the environment of Port Phillip Bay, Australia

Abstract

Assessment of environmental change over long periods of time is often impossible due to the absence of long-term quantitative data. Because it is not possible to collect such data retrospectively, qualitative data may provide some understanding of variation in environmental parameters over large temporal scales. The potential of qualitative data to yield valid and informative conclusions hinges on the extent of consistency in those data. The present study explored the potential for semi-structured interviews to serve as a data source for the retrospective assessment of environmental change. Two groups of people (anglers and divers) interacting with the environment of Port Phillip Bay, Australia, were questioned about their perceptions of change in that environment. Accounts covered more than six decades and several patterns emerged. Commercial dredging for scallop (Pecten fumatus) was assumed to have had a major negative impact on many taxa. Abundance of Snapper (Pagrus auratus) increased after dredging ceased in the mid-1990s though size and abundance were reduced relative to the early 1960s. The abundance of Flathead spp. (Neoplathycephalus richardsoni, Plathycephalus laevigatus & Plathycephalus arenarius) declined, and the spread of an introduced seastar (Asterias amurensis) was implicated in this decline. Importantly, the overall condition of Port Phillip Bay appears to have deteriorated on a large scale. Many species of fish and invertebrates purportedly disappeared or declined over the course of six decades. Similarly, a substantial reduction of macroalgae was noted. This preliminary study underscores the potential of qualitative data to assess environmental conditions in the past and illustrates the capacity for interdisciplinary research to aid in management and conservation.

Introduction

Assessment of human impacts on the distribution and abundance of plants and animals in particular ecosystems is important from the perspectives of conservation and management, but may be hampered by the absence of long-term quantitative data (Jackson, 1997). Often, rigorous monitoring programs are not initiated until presumed changes have already occurred (Lauck et al., 1998) and it is therefore difficult to judge the current status of populations of animals and plants relative to a satisfactory baseline (Dayton et al., 1998).

In some circumstances alternative methods may yield useful information about long-term changes within particular ecosystems. For example, museum collections provide one indirect method for assessing changes in the distribution of plants and animals (Levitan, 1992). In other instances people interacting on a long-term basis with the ecosystems in question to satisfy commercial, recreational or other needs, may possess knowledge which could provide useful information about change across time (Schultz et al., 2007, Parsons et al., 2009). However, it is necessary to assess the reliability of remembered records (Patton, 1999) and to allow that differences in perceptions of change may arise where different people use, or interact with, the same environment in different ways.

Port Phillip Bay in Victoria, Australia, is adjacent to the second largest city on the continent (Melbourne) and has been subject to a variety of impacts, particularly of anthropogenic nature, for more than a century (Fulton and Smith, 2002). Environmental studies of Port Phillip Bay date from the late 1960s, but most examined only a narrow suite of environmental parameters (Currie and Parry, 1999a). In general, data are scarce and comprehensive reference points regarding past patterns of abundance are virtually nonexistent.

The aim of the present study was to increase our understanding of changes in Port Phillip Bay over the past seven decades. To achieve this two groups of people who regularly interact with the marine environment of Port Phillip Bay were interviewed regarding their perceptions of change over that period. The study provides an initial examination of the value of using qualitative data, derived from interviews, to gain insight into changes that have occurred over periods when quantitative data are absent.

The two groups of people interviewed were recreational anglers and recreational divers. Both anglers and divers may be long-term users of the marine environment though each category of user experiences the organisms occupying that environment in a different way. Anglers experience the marine environment from outside it, though close to it, in the course of targeting some of the organisms – fish – that live within it. Divers experience the marine environment from within it, beneath the surface of the water. Even though a few of the interviewed divers engaged in spearfishing, the predominant motivation of this group was the pleasure gained through observation.

The present paper analyses (a) the existence and nature of consistency of statements concerning change both within and between the two groups of people interviewed, (b) possible sources of within-group and between-group inconsistency in statements made by the people interviewed and (c) the value of qualitative interview data for enhancing our understanding of relatively long-term biological changes in the ecosystem of Port Phillip Bay.

Because the biota and environment of Port Phillip Bay are under long term, and potentially increasing threat, from pollution and various forms of exploitation (e.g., Fulton and Smith, 2002, Currie and Parry, 1999a, Table 1) there is an urgent need for purposes of management and conservation to consolidate understanding of past conditions and patterns of change.