OHI Science | Citation policy
Compiled on Wed Oct 5 07:02:48 2022.
The global Ocean Health Index assesses ocean health for 220 coastal countries and territories and has been conducted every year starting in 2012. The Index describes how well we are sustainably managing 10 goals for ocean ecosystems which represent the full suite of benefits that people want and need from the ocean. These goals include: artisanal fishing opportunity, biodiversity, carbon storage, clean waters, coastal livelihoods and economies, coastal protection, food provision, natural products, sense of place, and tourism and recreation. Each goal is given a score ranging from 0 to 100, and the full suite of goal scores are then averaged to obtain an overall index score for each region.
For more information about the philosophy of the Ocean Health Index and model development see Halpern et al. (2012, 2015) and http://ohi-science.org/ohi-global/, which includes information about downloading global ocean health data.
The Ocean Health Index assesses ocean health which we define as how well we are sustainably managing the resources that we want and need from the ocean (e.g., tourism and recreation, food provisioning).
The OHI is considered a composite indicator because it combines many indicators into a comprehensive framework describing ocean health. This is in contrast to focusing on individual indicators, such as phosphate levels, sedimentation, biodiversity, etc. Individual indicators are important, but they provide limited information when it comes to evaluating how well an overall ecosystem is functioning. Another shortcoming of individual indicators is that they do not directly describe what we actually care about, and consequently, focusing on them can hinder communication. For example, most people do not directly care about nutrient pollution, however, we do care about its effects on the ocean’s ability to provide recreation and food.
Without an overall framework to evaluate indicators, certain indicators may be overemphasized relative to their true importance due to researcher bias (most researchers believe their area of study is the most important), trends in research (what is currently considered a hot topic and is funded), and availability of data (e.g., some data is easier to collect). A model that combines multiple indicators will inevitably have flaws, but at least we know which variables are included and how they are weighted.
One of the primary contributions of the OHI is that it recognizes people are an important part of the marine system. Both conservation and extractive use of ocean resources are valued, and consequently, scores are highest when we maximize the benefits we receive while maintaining sustainability so we can continue to receive benefits now and into the future. One temptation of indicator development is to focus only on the pressures that humans apply to systems. This makes sense because we want to be sure we are adequately protecting resources. However, eliminating all pressures on the ocean would require eliminating all contact between humans and the ocean. Beyond being unrealistic, this is undesirable because we would stop receiving all the benefits that we rely on from the ocean. The OHI is unique because it tracks both the pressures we put on oceans as well as the benefits we receive.
The global Ocean Health Index has been assessed every year since 2012. The primary goal of each yearly assessment is to calculate a new year of scores using the most recent data. Often, in addition to incorporating an additional year of data, we make improvements to models or decide to use different data sources. To ensure that scores for all years are comparable, we recalculate scores for previous scenario years for each assessment using new methods and data sources. For the current assessment, for example, in addition to calculating the current year’s scores, we recalculate scores for every year since 2012. Consequently, comparisons among years should always be performed using data from the same assessment year so trends in scores reflect changes to ocean health rather than changes to methods.
Not all data layers are reported through the most current assessment year, and consequently, the OHI scores are calculated using the most recent year of available data. Details on which years are used for each data layer are provided in Table 7.2.
We define ocean health as the sustainable delivery of ten widely-held public goals for ocean ecosystems (Table 2.1). These goals represent the full suite of benefits that people want and need from the ocean, including the traditional ‘goods and services’ people often consider (e.g., fish to eat, coastal protection from nearshore habitats) as well as benefits less commonly accounted for, such as cultural values and biodiversity. Within each region, scores, ranging from 0 to 100, are calculated for the 10 goals (section 5.2). Four of the goals are calculated from 2 subgoals. The subgoals are calculated independently (i.e., they are treated as if they are goals) and then combined into the goal status score (Table 2.2).
| Goal | Abbreviation | Description |
|---|---|---|
| Artisanal Fishing Opportunity | AO | The opportunity for small-scale fishers to supply catch for their families, members of their local communities, or sell in local markets |
| Biodiversity | BD | The conservation status of native marine species and key habitats that serve as a proxy for the suite of species that depend upon them |
| Carbon Storage | CS | The condition of coastal habitats that store and sequester atmospheric carbon |
| Clean Waters | CW | The degree to which ocean regions are free of contaminants such as chemicals, eutrophication, harmful algal blooms, disease pathogens, and trash |
| Coastal Livelihoods and Economies | LE | Coastal and ocean-dependent livelihoods (job quantity and quality) and economies (revenues) produced by marine sectors |
| Coastal Protection | CP | The amount of protection provided by marine and coastal habitats serving as natural buffers against incoming waves |
| Food Provision | FP | The sustainable harvest of seafood from wild-caught fisheries and mariculture |
| Natural Products | NP | The natural resources that are sustainably extracted from living marine resources |
| Sense of Place | SP | The conservation status of iconic species (e.g., salmon, whales) and geographic locations that contribute to cultural identity |
| Tourism and Recreation | TR | The value people have for experiencing and enjoying coastal areas through activities such as sailing, recreational fishing, beach-going, and bird watching |
| Subgoal | Goal | Abbreviation | Description |
|---|---|---|---|
| Habitat | Biodiversity | HAB | The status of key habitats that serve as a proxy for the suite of species that depend upon them |
| Species condition | Biodiversity | SPP | The conservation status of native marine species |
| Livelihoods | Coastal livelihoods and economies | LIV | Coastal and ocean-dependent livelihoods (job quantity and quality) produced by marine sectors |
| Economies | Coastal livelihoods and economies | ECO | Coastal and ocean-dependent economies (revenues) produced by marine sectors |
| Fisheries | Food provision | FIS | The sustainable harvest of seafood from wild-caught fisheries |
| Mariculture | Food provision | MAR | The sustainable harvest of seafood from mariculture practices |
| Iconic species | Sense of place | ICO | The conservation status of iconic species (e.g., salmon, whales) that contribute to cultural identity |
| Lasting special places | Sense of place | LSP | The conservation status of geographic locations that contribute to cultural identity |
Goal (and subgoal scores) are calculated using several variables (referred to as “dimensions”, Table 2.3). Goal scores (Section 5.2) are calculated as the average of current status (Section 5) and likely future status. Likely future status (Section 5.3) is the current status modified by variables (resilience, pressures, and trend) expected to influence future status.
Table 2.3. Dimension used to calculate an OHI goal score Goal scores are the average of current and likely future status. Likely future status adjusts current status scores based on pressures and resilience variables acting on the goal as well as recent trends in status.
| Dimension | Subdimension | Description | More information | Calculating |
|---|---|---|---|---|
| Current status | - | Current state of the goal relative to the desired “reference point”. Values range from 0-100. | Section 6. Goal models and data | Calculated using functions in ohi-global repo: https://github.com/OHI-Science/ohi-global/blob/draft/eez/conf/functions.R and the scenario_data_years.csv file (in same folder) |
| Predicted future status | Resilience | Variables such as good governance and ecological factors that provide resilience to pressures, and thus, are likely to improve future status. Values range from 0-100 | Section 5.3 Likely future status dimensions | Calculated using functions in ohicore package.And, files: resilience_categories.csv and resilience_matrix.csv located here: https://github.com/OHI-Science/ohi-global/tree/draft/eez/conf |
| Predicted future status | Pressure | Pressures stress the system and threaten future delivery of benefits, and thus, are likely to reduce future status. Values range from 0-100 | Section 5.3 Likely future status dimensions | Calculated using function in ohicore package. And, files: pressure_categories.csv and pressures_matrix.csv, located here: https://github.com/OHI-Science/ohi-global/tree/draft/eez/conf |
| Predicted future status | Trend | Average yearly change in status (typically estimated using most recent 5 years of data) multiplied by 5 to esimate five years into the future. Units are proportional change (absolute change/year is divided by the value of the earliest year) and range from -1 to 1 | Section 5.3 Likely future status dimensions | Calculated using functions from ohi-global repo: https://github.com/OHI-Science/ohi-global/blob/draft/eez/conf/functions.R and the scenario_data_years.csv file (in same folder) |
Figure 2.1. Relationship between OHI dimensions and scores This figure describes how the dimensions come together to calculate a goal score. This figure represents equations 4.3 and 4.5.